{
  "title": "Grouped and Ungrouped Frequency Distribution - Grade 9 CBSE",
  "total_questions": 100,
  "questions": [
    {"id": 1, "difficulty": "easy", "question": "What is a frequency distribution table?", "options": {"A": "A table showing sums of data", "B": "A table showing how often each value occurs", "C": "A table of random numbers", "D": "A table of mathematical formulas"}, "correct_answer": "B"},
    {"id": 2, "difficulty": "easy", "question": "In an ungrouped frequency distribution, data is arranged by:", "options": {"A": "Class intervals", "B": "Individual values", "C": "Percentages only", "D": "Graphs only"}, "correct_answer": "B"},
    {"id": 3, "difficulty": "easy", "question": "What is the frequency of a value in a distribution?", "options": {"A": "Its percentage", "B": "How many times it occurs", "C": "Its average", "D": "Its range"}, "correct_answer": "B"},
    {"id": 4, "difficulty": "easy", "question": "Grouped frequency distribution is used when:", "options": {"A": "Data has few distinct values", "B": "Data has many distinct values", "C": "Data is always small", "D": "Data has no numbers"}, "correct_answer": "B"},
    {"id": 5, "difficulty": "easy", "question": "What is a class interval in grouped data?", "options": {"A": "The middle value of data", "B": "A range of values grouped together", "C": "The highest value", "D": "The average value"}, "correct_answer": "B"},
    {"id": 6, "difficulty": "easy", "question": "If 5 students scored 80 marks, what is the frequency of mark 80?", "options": {"A": "80", "B": "5", "C": "85", "D": "75"}, "correct_answer": "B"},
    {"id": 7, "difficulty": "easy", "question": "Which distribution shows individual data points separately?", "options": {"A": "Grouped", "B": "Ungrouped", "C": "Both", "D": "Neither"}, "correct_answer": "B"},
    {"id": 8, "difficulty": "easy", "question": "What is the class mark of interval 10-20?", "options": {"A": "10", "B": "20", "C": "15", "D": "30"}, "correct_answer": "C"},
    {"id": 9, "difficulty": "easy", "question": "In grouped data, class limits are:", "options": {"A": "The smallest and largest values", "B": "The boundaries of each class", "C": "The frequencies", "D": "The averages"}, "correct_answer": "B"},
    {"id": 10, "difficulty": "easy", "question": "If class interval is 0-10, what is the upper limit?", "options": {"A": "0", "B": "10", "C": "5", "D": "15"}, "correct_answer": "B"},
    {"id": 11, "difficulty": "easy", "question": "What is the lower limit of class 20-30?", "options": {"A": "30", "B": "25", "C": "20", "D": "50"}, "correct_answer": "C"},
    {"id": 12, "difficulty": "easy", "question": "The difference between upper and lower class limits is called:", "options": {"A": "Frequency", "B": "Class width", "C": "Class mark", "D": "Range"}, "correct_answer": "B"},
    {"id": 13, "difficulty": "easy", "question": "For data: 5,5,6,7,7,7,8; frequency of 7 is:", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "C"},
    {"id": 14, "difficulty": "easy", "question": "Which is better for data with values 1,2,3,4,5?", "options": {"A": "Grouped distribution", "B": "Ungrouped distribution", "C": "Both equally good", "D": "Neither works"}, "correct_answer": "B"},
    {"id": 15, "difficulty": "easy", "question": "Class boundaries help to:", "options": {"A": "Eliminate gaps between classes", "B": "Increase frequency", "C": "Decrease frequency", "D": "Find average"}, "correct_answer": "A"},
    {"id": 16, "difficulty": "easy", "question": "If frequency of value 10 is 4, it means:", "options": {"A": "Value 10 appears 4 times", "B": "Value is 4", "C": "Total is 14", "D": "Average is 10"}, "correct_answer": "A"},
    {"id": 17, "difficulty": "easy", "question": "What is true about class width?", "options": {"A": "It varies within same table", "B": "It is usually constant", "C": "It is always 5", "D": "It equals frequency"}, "correct_answer": "B"},
    {"id": 18, "difficulty": "easy", "question": "For class 30-40, class mark is:", "options": {"A": "30", "B": "40", "C": "35", "D": "70"}, "correct_answer": "C"},
    {"id": 19, "difficulty": "easy", "question": "Ungrouped data shows:", "options": {"A": "Ranges only", "B": "Individual values", "C": "Only averages", "D": "Only graphs"}, "correct_answer": "B"},
    {"id": 20, "difficulty": "easy", "question": "Grouped data is organized into:", "options": {"A": "Lists", "B": "Class intervals", "C": "Single values", "D": "Equations"}, "correct_answer": "B"},
    
    {"id": 21, "difficulty": "medium", "question": "Given marks: 45,50,55,60,65,70,75. Create class intervals of width 10 starting from 45. What is the frequency of class 55-65?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "B"},
    {"id": 22, "difficulty": "medium", "question": "Data: 12,15,18,12,20,15,12,18,15,12. What is the frequency of 15 in ungrouped distribution?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 23, "difficulty": "medium", "question": "For grouped data with intervals 0-10,10-20,20-30, what is the class width?", "options": {"A": "5", "B": "10", "C": "15", "D": "20"}, "correct_answer": "B"},
    {"id": 24, "difficulty": "medium", "question": "Heights (cm): 150,152,155,157,160,162,165,167,170. If grouped as 150-155,155-160,etc., what is frequency of 155-160?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "A"},
    {"id": 25, "difficulty": "medium", "question": "In a survey, ages recorded: 15,16,17,15,18,16,15,19,16,15. Which age has highest frequency?", "options": {"A": "15", "B": "16", "C": "17", "D": "18"}, "correct_answer": "A"},
    {"id": 26, "difficulty": "medium", "question": "Class intervals: 20-30,30-40,40-50. What are the class boundaries for 30-40?", "options": {"A": "25-35", "B": "30-40", "C": "29.5-40.5", "D": "20-50"}, "correct_answer": "C"},
    {"id": 27, "difficulty": "medium", "question": "Test scores: 35,42,48,52,58,62,65,68,72,78. Group as 35-45,45-55,etc. Frequency of 55-65?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "C"},
    {"id": 28, "difficulty": "medium", "question": "What is the class mark of interval 25-35?", "options": {"A": "25", "B": "35", "C": "30", "D": "60"}, "correct_answer": "C"},
    {"id": 29, "difficulty": "medium", "question": "For data: 8,12,15,18,22,25,28,32,35,38. Create classes of width 10 from 5. How many classes?", "options": {"A": "3", "B": "4", "C": "5", "D": "6"}, "correct_answer": "B"},
    {"id": 30, "difficulty": "medium", "question": "In a frequency table, sum of all frequencies equals:", "options": {"A": "Class width", "B": "Total observations", "C": "Class mark", "D": "Range"}, "correct_answer": "B"},
    {"id": 31, "difficulty": "medium", "question": "Data: 21,23,24,26,27,28,29,30,31,33. Group as 20-25,25-30,30-35. Frequency of 25-30?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 32, "difficulty": "medium", "question": "If class interval is written as 10-20,20-30, there is ambiguity at:", "options": {"A": "10", "B": "20", "C": "30", "D": "All values"}, "correct_answer": "B"},
    {"id": 33, "difficulty": "medium", "question": "To avoid ambiguity in class intervals, we use:", "options": {"A": "Class marks", "B": "Class boundaries", "C": "Only frequencies", "D": "Graphs"}, "correct_answer": "B"},
    {"id": 34, "difficulty": "medium", "question": "Temperature readings: 18.5,19.0,19.5,20.0,20.5,21.0,21.5°C. Group as 18-19,19-20,20-21,21-22. How many in 20-21?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "B"},
    {"id": 35, "difficulty": "medium", "question": "In exclusive method, class intervals are:", "options": {"A": "Overlapping", "B": "Non-overlapping", "C": "Mixed", "D": "Random"}, "correct_answer": "B"},
    {"id": 36, "difficulty": "medium", "question": "Weights (kg): 45,48,52,55,58,60,62,65,68,70. Group as 45-50,50-55,55-60,60-65,65-70. Frequency of 60-65?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "B"},
    {"id": 37, "difficulty": "medium", "question": "What is the upper class boundary for interval 15-25?", "options": {"A": "15", "B": "25", "C": "20", "D": "25.5"}, "correct_answer": "D"},
    {"id": 38, "difficulty": "medium", "question": "For inclusive classes 10-19,20-29,30-39, the class width is:", "options": {"A": "9", "B": "10", "C": "11", "D": "12"}, "correct_answer": "B"},
    {"id": 39, "difficulty": "medium", "question": "Data points: 7,8,9,10,11,12,13,14,15. If grouped as 7-10 and 11-14, what percentage in first group?", "options": {"A": "33.3%", "B": "44.4%", "C": "55.5%", "D": "66.6%"}, "correct_answer": "B"},
    {"id": 40, "difficulty": "medium", "question": "In a frequency distribution, if class intervals are 0-10,10-20,20-30, and a value is exactly 20, where does it go?", "options": {"A": "10-20", "B": "20-30", "C": "Both", "D": "Neither"}, "correct_answer": "B"},
    {"id": 41, "difficulty": "medium", "question": "Create ungrouped distribution for: A,B,A,C,B,A,D,A,B. Frequency of A?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 42, "difficulty": "medium", "question": "Monthly savings (₹): 500,550,600,650,700,750,800,850,900,950. Group as 500-600,600-700,700-800,800-900,900-1000. How many in 700-800?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "B"},
    {"id": 43, "difficulty": "medium", "question": "What is the lower class boundary for interval 40-50?", "options": {"A": "40", "B": "50", "C": "39.5", "D": "45"}, "correct_answer": "C"},
    {"id": 44, "difficulty": "medium", "question": "For data with range 0-100, if we want 5 classes, approximate class width?", "options": {"A": "10", "B": "15", "C": "20", "D": "25"}, "correct_answer": "C"},
    {"id": 45, "difficulty": "medium", "question": "Ages: 13,14,15,16,17,18,19,20. Create classes 13-15,16-18,19-21. Frequency of 16-18?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 46, "difficulty": "medium", "question": "In grouped data, why do we use class marks?", "options": {"A": "To represent entire class", "B": "To show frequencies", "C": "To find boundaries", "D": "For color coding"}, "correct_answer": "A"},
    {"id": 47, "difficulty": "medium", "question": "Test marks: 25,30,35,40,45,50,55,60,65,70. Group as 25-35,35-45,45-55,55-65,65-75. Frequency of 45-55?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "B"},
    {"id": 48, "difficulty": "medium", "question": "If class boundaries are 29.5-39.5, what is the class interval in inclusive form?", "options": {"A": "29-39", "B": "30-39", "C": "30-40", "D": "29-40"}, "correct_answer": "B"},
    {"id": 49, "difficulty": "medium", "question": "For data: 12,15,18,21,24,27,30,33,36. Create 3 equal classes. What is first class?", "options": {"A": "12-20", "B": "12-21", "C": "12-24", "D": "12-18"}, "correct_answer": "C"},
    {"id": 50, "difficulty": "medium", "question": "Number of siblings: 0,1,2,3,4,5. Frequency: 8,12,7,3,2,1. Total students?", "options": {"A": "30", "B": "31", "C": "32", "D": "33"}, "correct_answer": "D"},
    {"id": 51, "difficulty": "medium", "question": "Heights: 150-155cm: 4 students, 155-160: 6, 160-165: 8, 165-170: 2. Total students?", "options": {"A": "18", "B": "19", "C": "20", "D": "21"}, "correct_answer": "C"},
    {"id": 52, "difficulty": "medium", "question": "For class interval 15-25, if converted to boundaries, we get:", "options": {"A": "14.5-25.5", "B": "15.5-25.5", "C": "14.5-24.5", "D": "15-25"}, "correct_answer": "A"},
    {"id": 53, "difficulty": "medium", "question": "In a frequency polygon, points are plotted using:", "options": {"A": "Class boundaries and frequencies", "B": "Class marks and frequencies", "C": "Lower limits only", "D": "Upper limits only"}, "correct_answer": "B"},
    {"id": 54, "difficulty": "medium", "question": "Data: 5,10,15,20,25,30,35,40,45,50. Create classes width 15 starting 0. How many in 15-30?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "A"},
    {"id": 55, "difficulty": "medium", "question": "If a value falls on class boundary, convention says place it in:", "options": {"A": "Lower class", "B": "Upper class", "C": "Both", "D": "Middle class"}, "correct_answer": "B"},
    {"id": 56, "difficulty": "medium", "question": "Weights: 40,42,45,48,50,52,55,58,60,62. Group as 40-45,45-50,50-55,55-60,60-65. Frequency of 50-55?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "C"},
    {"id": 57, "difficulty": "medium", "question": "For class 20-30, class mark is 25. For 30-40, class mark is:", "options": {"A": "30", "B": "35", "C": "40", "D": "45"}, "correct_answer": "B"},
    {"id": 58, "difficulty": "medium", "question": "In a histogram, bars touch each other because:", "options": {"A": "Data is continuous", "B": "Data is discrete", "C": "It looks better", "D": "Frequencies are high"}, "correct_answer": "A"},
    {"id": 59, "difficulty": "medium", "question": "Tally marks are used to:", "options": {"A": "Calculate mean", "B": "Count frequencies", "C": "Find range", "D": "Draw graphs"}, "correct_answer": "B"},
    {"id": 60, "difficulty": "medium", "question": "Data: 18,22,25,28,31,34,37,40,43,46. Group as 15-25,25-35,35-45,45-55. Frequency of 25-35?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"},
    {"id": 61, "difficulty": "medium", "question": "If total observations=50 and sum of frequencies=45, there is:", "options": {"A": "No error", "B": "Error in counting", "C": "Missing data", "D": "Grouping error"}, "correct_answer": "B"},
    {"id": 62, "difficulty": "medium", "question": "Class intervals: 0-5,5-10,10-15,15-20. Class width?", "options": {"A": "4", "B": "5", "C": "6", "D": "7"}, "correct_answer": "B"},
    {"id": 63, "difficulty": "medium", "question": "For data with minimum=10,max=90, if using class width=20, how many classes?", "options": {"A": "3", "B": "4", "C": "5", "D": "6"}, "correct_answer": "B"},
    {"id": 64, "difficulty": "medium", "question": "In a frequency table, relative frequency =", "options": {"A": "Frequency/total", "B": "Total/frequency", "C": "Frequency×total", "D": "Frequency−total"}, "correct_answer": "A"},
    {"id": 65, "difficulty": "medium", "question": "Data: 3,5,7,9,11,13,15,17,19,21. Group as 3-8,8-13,13-18,18-23. Frequency of 13-18?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 66, "difficulty": "medium", "question": "If class boundaries are 19.5-29.5, the inclusive class is:", "options": {"A": "19-29", "B": "20-29", "C": "20-30", "D": "19-30"}, "correct_answer": "B"},
    {"id": 67, "difficulty": "medium", "question": "For class interval '10-20', which is NOT true?", "options": {"A": "Lower limit=10", "B": "Upper limit=20", "C": "Class mark=15", "D": "Class width=15"}, "correct_answer": "D"},
    {"id": 68, "difficulty": "medium", "question": "Temperatures: 20,21,22,23,24,25,26,27,28,29°C. Group as 20-23,23-26,26-29. Frequency of 23-26?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 69, "difficulty": "medium", "question": "In exclusive method, if interval is 10-20, it includes:", "options": {"A": "10 but not 20", "B": "20 but not 10", "C": "Both 10 and 20", "D": "Neither 10 nor 20"}, "correct_answer": "A"},
    {"id": 70, "difficulty": "medium", "question": "Ages: 10,11,12,13,14,15,16,17,18,19. Create classes 10-12,13-15,16-18,19-21. Frequency of 16-18?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 71, "difficulty": "medium", "question": "For data with values 100-199, suitable class intervals?", "options": {"A": "100-150,150-200", "B": "100-120,120-140", "C": "100-125,125-150,150-175,175-200", "D": "100-200 only"}, "correct_answer": "C"},
    {"id": 72, "difficulty": "medium", "question": "If frequency of class 30-40 is 8, and total=40, relative frequency=?", "options": {"A": "0.1", "B": "0.2", "C": "0.3", "D": "0.4"}, "correct_answer": "B"},
    {"id": 73, "difficulty": "medium", "question": "Scores: 45,50,55,60,65,70,75,80. Group as 45-55,55-65,65-75,75-85. Frequency of 65-75?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "B"},
    {"id": 74, "difficulty": "medium", "question": "In a grouped distribution, we lose:", "options": {"A": "Individual values", "B": "Total count", "C": "Class width", "D": "Range"}, "correct_answer": "A"},
    {"id": 75, "difficulty": "medium", "question": "Data: 14,16,18,20,22,24,26,28,30,32. Group as 14-20,20-26,26-32. Frequency of 20-26?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 76, "difficulty": "medium", "question": "If class width=10 and first lower limit=15, third class interval?", "options": {"A": "25-35", "B": "30-40", "C": "35-45", "D": "40-50"}, "correct_answer": "C"},
    {"id": 77, "difficulty": "medium", "question": "For inclusive classes 1-10,11-20,21-30, class width after adjustment?", "options": {"A": "9", "B": "10", "C": "11", "D": "12"}, "correct_answer": "B"},
    {"id": 78, "difficulty": "medium", "question": "Marks: 0-10:5,10-20:8,20-30:12,30-40:10,40-50:5. Total students?", "options": {"A": "35", "B": "38", "C": "40", "D": "42"}, "correct_answer": "C"},
    {"id": 79, "difficulty": "medium", "question": "Heights: 140-150:3,150-160:7,160-170:10,170-180:6,180-190:4. Percentage in 160-170?", "options": {"A": "20%", "B": "25%", "C": "30%", "D": "33.3%"}, "correct_answer": "D"},
    {"id": 80, "difficulty": "medium", "question": "In cumulative frequency, we add frequencies:", "options": {"A": "From top to bottom", "B": "From bottom to top", "C": "Randomly", "D": "Only even numbers"}, "correct_answer": "B"},
    
    {"id": 81, "difficulty": "hard", "question": "Given data: 12,15,18,21,24,27,30,33,36,39,42,45,48,51,54. Create grouped distribution with 5 classes. What is frequency of third class if classes are equal width?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 82, "difficulty": "hard", "question": "For data with range 25-75, if we want classes with width 8 starting from 25, what are the class boundaries for second class?", "options": {"A": "32.5-40.5", "B": "33-41", "C": "32-40", "D": "33.5-41.5"}, "correct_answer": "A"},
    {"id": 83, "difficulty": "hard", "question": "In a survey of 50 students, marks distribution: 0-20:5,20-40:12,40-60:18,60-80:10,80-100:5. What percentage scored above 60?", "options": {"A": "20%", "B": "25%", "C": "30%", "D": "35%"}, "correct_answer": "C"},
    {"id": 84, "difficulty": "hard", "question": "Given: Class intervals 10-20,20-30,30-40 with frequencies 8,12,10. Convert to class boundaries and find width.", "options": {"A": "9.5", "B": "10", "C": "10.5", "D": "11"}, "correct_answer": "B"},
    {"id": 85, "difficulty": "hard", "question": "Data: 0.5,1.2,1.8,2.3,2.9,3.4,3.8,4.2,4.7,5.1. Create classes 0-1,1-2,2-3,3-4,4-5,5-6. Frequency of 3-4?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "B"},
    {"id": 86, "difficulty": "hard", "question": "For grouped data with classes 15-25,25-35,35-45, if frequency of 25-35 is 15 and total=60, what is relative frequency of this class?", "options": {"A": "0.2", "B": "0.25", "C": "0.3", "D": "0.35"}, "correct_answer": "B"},
    {"id": 87, "difficulty": "hard", "question": "Given: Values 23,27,31,35,39,43,47,51,55,59. If grouped as 20-30,30-40,40-50,50-60, which value causes ambiguity?", "options": {"A": "30", "B": "40", "C": "50", "D": "All above"}, "correct_answer": "D"},
    {"id": 88, "difficulty": "hard", "question": "In a frequency distribution, if class marks are 25,35,45,55 and class width is 10, what are the class intervals?", "options": {"A": "20-30,30-40,40-50,50-60", "B": "25-35,35-45,45-55,55-65", "C": "22.5-27.5,etc.", "D": "20-30,40-50,etc."}, "correct_answer": "A"},
    {"id": 89, "difficulty": "hard", "question": "Data has minimum=18, maximum=72. Want approximately 6 classes. Best class width?", "options": {"A": "8", "B": "9", "C": "10", "D": "11"}, "correct_answer": "C"},
    {"id": 90, "difficulty": "hard", "question": "For class boundaries 14.5-24.5,24.5-34.5,34.5-44.5, what are the class marks?", "options": {"A": "19.5,29.5,39.5", "B": "20,30,40", "C": "19,29,39", "D": "20.5,30.5,40.5"}, "correct_answer": "C"},
    {"id": 91, "difficulty": "hard", "question": "Given frequency distribution: Class 0-10:4,10-20:7,20-30:12,30-40:9,40-50:3. Find cumulative frequency up to class 20-30.", "options": {"A": "11", "B": "16", "C": "23", "D": "32"}, "correct_answer": "C"},
    {"id": 92, "difficulty": "hard", "question": "Data points: 5,8,12,15,18,22,25,28,32,35,38,42,45,48,52. Create classes width=10 starting 0. How many data points in 20-30?", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "C"},
    {"id": 93, "difficulty": "hard", "question": "For data with values from 0.1 to 4.9, if using class width 0.5 starting 0.0, how many classes?", "options": {"A": "8", "B": "9", "C": "10", "D": "11"}, "correct_answer": "C"},
    {"id": 94, "difficulty": "hard", "question": "In a grouped distribution with classes 100-200,200-300,etc., if a value is 200, where should it be placed conventionally?", "options": {"A": "100-200", "B": "200-300", "C": "Either", "D": "Split between both"}, "correct_answer": "B"},
    {"id": 95, "difficulty": "hard", "question": "Given: Class intervals 5-15,15-25,25-35 with frequencies 6,10,8. Find relative frequency of 15-25 as percentage.", "options": {"A": "25%", "B": "33.3%", "C": "41.7%", "D": "50%"}, "correct_answer": "C"},
    {"id": 96, "difficulty": "hard", "question": "Data: 12.3,14.7,16.2,18.9,20.4,22.1,23.8,25.5,27.3,29.0. Group with width 4 starting 12. Frequency of class 20-24?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 97, "difficulty": "hard", "question": "For a dataset, range=48, number of classes desired=6. Minimum class width needed?", "options": {"A": "7", "B": "8", "C": "9", "D": "10"}, "correct_answer": "B"},
    {"id": 98, "difficulty": "hard", "question": "Given inclusive classes: 10-19,20-29,30-39. Convert to exclusive form.", "options": {"A": "9.5-19.5,19.5-29.5,29.5-39.5", "B": "10-20,20-30,30-40", "C": "10.5-19.5,20.5-29.5,30.5-39.5", "D": "9.5-20.5,19.5-30.5,29.5-40.5"}, "correct_answer": "A"},
    {"id": 99, "difficulty": "hard", "question": "In a frequency table, if sum of frequencies=75 but actual count=80, what is likely error?", "options": {"A": "Missing class", "B": "Counting error", "C": "Wrong class width", "D": "Incorrect boundaries"}, "correct_answer": "B"},
    {"id": 100, "difficulty": "hard", "question": "Data values: 0,3,7,10,13,16,19,22,25,28,31,34,37,40. Create grouped distribution with 4 equal classes. What is frequency of highest class?", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "C"}
  ]
}