{
  "title": "Mean, Median, Mode - Grade 9 ICSE",
  "total_questions": 60,
  "questions": [
    {"id": 1, "difficulty": "easy", "question": "📊 What is the common name for the 'average' of a set of numbers? ", "options": {"A": "Median", "B": "Mode", "C": "Mean", "D": "Range"}, "correct_answer": "C"},
    {"id": 2, "difficulty": "easy", "question": "🔢 To find the mean, you add all numbers and divide by... ", "options": {"A": "the largest number", "B": "the number of items", "C": "the smallest number", "D": "2"}, "correct_answer": "B"},
    {"id": 3, "difficulty": "easy", "question": "🎯 The middle value when data is arranged in order is called the... ", "options": {"A": "Mean", "B": "Median", "C": "Mode", "D": "Average"}, "correct_answer": "B"},
    {"id": 4, "difficulty": "easy", "question": "📈 The value that appears most often in a data set is the... ", "options": {"A": "Median", "B": "Mean", "C": "Mode", "D": "Mid-point"}, "correct_answer": "C"},
    {"id": 5, "difficulty": "easy", "question": "📊 Find the mean of 4, 6, 8. ", "options": {"A": "5", "B": "6", "C": "7", "D": "8"}, "correct_answer": "B"},
    {"id": 6, "difficulty": "easy", "question": "🔢 Find the median of 3, 5, 7. ", "options": {"A": "3", "B": "5", "C": "7", "D": "6"}, "correct_answer": "B"},
    {"id": 7, "difficulty": "easy", "question": "🎯 Find the mode of 2, 3, 3, 4, 5. ", "options": {"A": "2", "B": "3", "C": "4", "D": "5"}, "correct_answer": "B"},
    {"id": 8, "difficulty": "easy", "question": "📈 A data set can have more than one mode. (True/False) ", "options": {"A": "True", "B": "False", "C": "Only for mean", "D": "Only for median"}, "correct_answer": "A"},
    {"id": 9, "difficulty": "easy", "question": "📊 Which measure of central tendency can be found just by looking at the data? ", "options": {"A": "Mean", "B": "Median", "C": "Mode", "D": "Range"}, "correct_answer": "C"},
    {"id": 10, "difficulty": "easy", "question": "🔢 For the numbers 10, 20, 30, the mean is? ", "options": {"A": "15", "B": "20", "C": "25", "D": "30"}, "correct_answer": "B"},
    {"id": 11, "difficulty": "easy", "question": "🎯 If all numbers in a data set are the same, the mean, median, and mode are... ", "options": {"A": "all different", "B": "all equal to that number", "C": "zero", "D": "cannot be found"}, "correct_answer": "B"},
    {"id": 12, "difficulty": "easy", "question": "📈 The mean of 5 numbers is 10. Their sum is? ", "options": {"A": "2", "B": "10", "C": "50", "D": "15"}, "correct_answer": "C"},
    {"id": 13, "difficulty": "easy", "question": "📊 To find the median, the data must be arranged in... ", "options": {"A": "random order", "B": "ascending or descending order", "C": "alphabetical order", "D": "reverse order"}, "correct_answer": "B"},
    {"id": 14, "difficulty": "easy", "question": "🔢 For an even number of items, the median is the average of the two... ", "options": {"A": "middle values", "B": "end values", "C": "first and last", "D": "modes"}, "correct_answer": "A"},
    {"id": 15, "difficulty": "easy", "question": "🎯 Find the median of 8, 3, 5. (Arrange first!) ", "options": {"A": "3", "B": "5", "C": "8", "D": "6"}, "correct_answer": "B"},
    {"id": 16, "difficulty": "easy", "question": "📈 If a data set has no repeating values, it has... ", "options": {"A": "no mode", "B": "one mode", "C": "two modes", "D": "infinite modes"}, "correct_answer": "A"},
    {"id": 17, "difficulty": "easy", "question": "📊 Which measure is affected by extreme values (very high or low)? ", "options": {"A": "Mean", "B": "Median", "C": "Mode", "D": "Both median and mode"}, "correct_answer": "A"},
    {"id": 18, "difficulty": "easy", "question": "🔢 The mean of 2, 4, 6, 8, 10 is? ", "options": {"A": "5", "B": "6", "C": "7", "D": "8"}, "correct_answer": "B"},
    {"id": 19, "difficulty": "easy", "question": "🎯 The mode of 1, 1, 2, 3, 4 is? ", "options": {"A": "1", "B": "2", "C": "3", "D": "4"}, "correct_answer": "A"},
    {"id": 20, "difficulty": "easy", "question": "📈 If the mean of three numbers is 12, their sum is? ", "options": {"A": "4", "B": "12", "C": "24", "D": "36"}, "correct_answer": "D"},
    {"id": 21, "difficulty": "medium", "question": "📊 Find the mean of: 15, 20, 25, 30, 35. ", "options": {"A": "20", "B": "25", "C": "30", "D": "35"}, "correct_answer": "B"},
    {"id": 22, "difficulty": "medium", "question": "🔢 Find the median of: 12, 17, 22, 27, 32, 37. ", "options": {"A": "22", "B": "24.5", "C": "27", "D": "29.5"}, "correct_answer": "B"},
    {"id": 23, "difficulty": "medium", "question": "🎯 Find the mode of: 5, 7, 7, 8, 9, 9, 9, 10. ", "options": {"A": "7", "B": "8", "C": "9", "D": "10"}, "correct_answer": "C"},
    {"id": 24, "difficulty": "medium", "question": "📈 If the mean of 4, x, 8 is 6, find x. ", "options": {"A": "4", "B": "5", "C": "6", "D": "7"}, "correct_answer": "C"},
    {"id": 25, "difficulty": "medium", "question": "📊 A student scored 75, 80, 85 in three tests. What should he score in the fourth to have a mean of 82? ", "options": {"A": "82", "B": "85", "C": "88", "D": "90"}, "correct_answer": "C"},
    {"id": 26, "difficulty": "medium", "question": "🔢 The median of 11, 13, 17, 19, 23 is? ", "options": {"A": "13", "B": "17", "C": "19", "D": "20"}, "correct_answer": "B"},
    {"id": 27, "difficulty": "medium", "question": "🎯 The mode of 2, 3, 4, 4, 5, 5, 5, 6, 6 is? ", "options": {"A": "4", "B": "5", "C": "6", "D": "4 and 5"}, "correct_answer": "B"},
    {"id": 28, "difficulty": "medium", "question": "📈 The mean of five numbers is 20. If four numbers are 15, 20, 25, 30, find the fifth. ", "options": {"A": "10", "B": "15", "C": "20", "D": "25"}, "correct_answer": "A"},
    {"id": 29, "difficulty": "medium", "question": "📊 Which is not a measure of central tendency? ", "options": {"A": "Mean", "B": "Median", "C": "Mode", "D": "Range"}, "correct_answer": "D"},
    {"id": 30, "difficulty": "medium", "question": "🔢 For data: 10, 12, 14, 16, 18, the mean is 14. If each number is increased by 2, the new mean is? ", "options": {"A": "14", "B": "16", "C": "18", "D": "20"}, "correct_answer": "B"},
    {"id": 31, "difficulty": "medium", "question": "🎯 For grouped data, the class with the highest frequency is called the... ", "options": {"A": "mean class", "B": "median class", "C": "modal class", "D": "range class"}, "correct_answer": "C"},
    {"id": 32, "difficulty": "medium", "question": "📈 The sum of deviations of data from their mean is always... ", "options": {"A": "positive", "B": "negative", "C": "zero", "D": "one"}, "correct_answer": "C"},
    {"id": 33, "difficulty": "medium", "question": "📊 The median of 6, 8, 10, 12, 14, 16 is? ", "options": {"A": "10", "B": "11", "C": "12", "D": "13"}, "correct_answer": "B"},
    {"id": 34, "difficulty": "medium", "question": "🔢 If the mode of 3, 5, 7, 5, x, 9 is 5, then x is? ", "options": {"A": "3", "B": "5", "C": "7", "D": "9"}, "correct_answer": "B"},
    {"id": 35, "difficulty": "medium", "question": "🎯 The mean of first five natural numbers is? ", "options": {"A": "3", "B": "4", "C": "5", "D": "6"}, "correct_answer": "A"},
    {"id": 36, "difficulty": "medium", "question": "📈 In a factory, the daily wages of 5 workers are ₹300, ₹350, ₹400, ₹450, ₹500. The median wage is? ", "options": {"A": "₹350", "B": "₹400", "C": "₹450", "D": "₹425"}, "correct_answer": "B"},
    {"id": 37, "difficulty": "medium", "question": "📊 The mode is the most... value. ", "options": {"A": "frequent", "B": "central", "C": "average", "D": "recent"}, "correct_answer": "A"},
    {"id": 38, "difficulty": "medium", "question": "🔢 If the mean of a, b, c is 10, then the mean of a+2, b+2, c+2 is? ", "options": {"A": "10", "B": "12", "C": "14", "D": "16"}, "correct_answer": "B"},
    {"id": 39, "difficulty": "medium", "question": "🎯 The median is a better average than the mean when there are... ", "options": {"A": "no extreme values", "B": "extreme values", "C": "all values equal", "D": "only two values"}, "correct_answer": "B"},
    {"id": 40, "difficulty": "medium", "question": "📈 The mean of 10 numbers is 15. If one number is removed, the mean becomes 14. The removed number is? ", "options": {"A": "10", "B": "15", "C": "20", "D": "24"}, "correct_answer": "D"},
    {"id": 41, "difficulty": "hard", "question": "📊 Find the mean of first 10 even natural numbers. ", "options": {"A": "10", "B": "11", "C": "12", "D": "13"}, "correct_answer": "B"},
    {"id": 42, "difficulty": "hard", "question": "🔢 Find the median of: 41, 43, 47, 53, 59, 61, 67. ", "options": {"A": "53", "B": "55", "C": "56", "D": "59"}, "correct_answer": "A"},
    {"id": 43, "difficulty": "hard", "question": "🎯 Find the mode of: 1, 3, 5, 7, 9, 1, 3, 5, 3, 5, 3. ", "options": {"A": "1", "B": "3", "C": "5", "D": "7"}, "correct_answer": "B"},
    {"id": 44, "difficulty": "hard", "question": "📈 The mean of 25 numbers is 8. If 2 is added to each number, the new mean is? ", "options": {"A": "8", "B": "10", "C": "25", "D": "200"}, "correct_answer": "B"},
    {"id": 45, "difficulty": "hard", "question": "📊 The mean of 5 numbers is 18. If one number is excluded, their mean is 16. The excluded number is? ", "options": {"A": "18", "B": "20", "C": "26", "D": "30"}, "correct_answer": "C"},
    {"id": 46, "difficulty": "hard", "question": "🔢 The median of data 15, 12, 10, 18, 22, 14, 20 (arranged in order) is? ", "options": {"A": "15", "B": "16", "C": "18", "D": "20"}, "correct_answer": "A"},
    {"id": 47, "difficulty": "hard", "question": "🎯 A data set has 6 numbers with mean 12. Another number is added, and the new mean is 13. The added number is? ", "options": {"A": "13", "B": "18", "C": "19", "D": "20"}, "correct_answer": "C"},
    {"id": 48, "difficulty": "hard", "question": "📈 The mode of 2, 3, 4, 3, 5, 3, 6, 4, 3, 4, 5, 4 is? (Hint: Count frequencies) ", "options": {"A": "3", "B": "4", "C": "3 and 4 (bimodal)", "D": "5"}, "correct_answer": "C"},
    {"id": 49, "difficulty": "hard", "question": "📊 The mean of three numbers is 15. The median is 16, and the mode is 14. The three numbers are? ", "options": {"A": "14, 14, 16", "B": "14, 16, 18", "C": "14, 16, 15", "D": "14, 16, 20"}, "correct_answer": "B"},
    {"id": 50, "difficulty": "hard", "question": "🔢 The sum of 10 numbers is 250. Their mean is? ", "options": {"A": "10", "B": "25", "C": "250", "D": "2500"}, "correct_answer": "B"},
    {"id": 51, "difficulty": "hard", "question": "🎯 For grouped data with modal class 20-30 and frequencies: 10-20(5), 20-30(12), 30-40(8), the mode lies in which class? ", "options": {"A": "10-20", "B": "20-30", "C": "30-40", "D": "Cannot say"}, "correct_answer": "B"},
    {"id": 52, "difficulty": "hard", "question": "📈 The arithmetic mean is also called the... ", "options": {"A": "simple average", "B": "weighted average", "C": "geometric mean", "D": "harmonic mean"}, "correct_answer": "A"},
    {"id": 53, "difficulty": "hard", "question": "📊 If the mean of a, b, c, d is 10, then the mean of 2a, 2b, 2c, 2d is? ", "options": {"A": "10", "B": "20", "C": "30", "D": "40"}, "correct_answer": "B"},
    {"id": 54, "difficulty": "hard", "question": "🔢 The median of 7 numbers is 10. If the highest number is doubled, the median... ", "options": {"A": "doubles", "B": "remains 10", "C": "becomes 20", "D": "cannot say"}, "correct_answer": "B"},
    {"id": 55, "difficulty": "hard", "question": "🎯 The mean of 1, 2, 3, ..., n is? (Hint: Sum of first n natural numbers is n(n+1)/2) ", "options": {"A": "n/2", "B": "(n+1)/2", "C": "n(n+1)/2", "D": "(n-1)/2"}, "correct_answer": "B"},
    {"id": 56, "difficulty": "hard", "question": "📈 The mode of the data: 8, 6, 4, 5, 6, 3, 8, 6, 5, 6, 4, 6 is 6. What is its frequency? ", "options": {"A": "3", "B": "4", "C": "5", "D": "6"}, "correct_answer": "C"},
    {"id": 57, "difficulty": "hard", "question": "📊 The mean of 100 numbers is 50. If two numbers 60 and 80 are removed, the new mean is? (Assume sum changes) ", "options": {"A": "49", "B": "50", "C": "51", "D": "52"}, "correct_answer": "A"},
    {"id": 58, "difficulty": "hard", "question": "🔢 For a symmetrical distribution, mean, median, and mode are... ", "options": {"A": "all equal", "B": "all different", "C": "mean = median only", "D": "median = mode only"}, "correct_answer": "A"},
    {"id": 59, "difficulty": "hard", "question": "🎯 If the mean of 9 observations is 36 and the mean of first 5 is 32, the mean of last 4 is? ", "options": {"A": "40", "B": "41", "C": "42", "D": "45"}, "correct_answer": "B"},
    {"id": 60, "difficulty": "hard", "question": "✅ Which measure of central tendency is used to find the average of categorical data (like favorite color)? ", "options": {"A": "Mean", "B": "Median", "C": "Mode", "D": "Range"}, "correct_answer": "C"}
  ]
}