Multiple choice

Given table shows the marks scored by various students in a class test. Find the mean of the given data. Marks 41 - 50 51 - 60 61 - 70 71 - 80 81 - 90 91 - 100 Frequency 8 17 12 14 20 3

  1. 69.55

  2. 72.48

  3. 88.67

  4. 97.24
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A Correct answer
Explanation

Use the midpoints of the marks: 45.5, 55.5, 65.5, 75.5, 85.5, 95.5. Multiply by frequencies: 8*45.5=364, 17*55.5=943.5, 12*65.5=786, 14*75.5=1057, 20*85.5=1710, 3*95.5=286.5. Sum = 5147. Total frequency = 74. Mean = 5147/74 = 69.554.

AI explanation

To find the mean of grouped data, we use the class marks 45.5, 55.5, 65.5, 75.5, 85.5, and 95.5. Multiplying these marks by their respective frequencies of 8, 17, 12, 14, 20, and 3 gives a total sum of 5147. Dividing this sum by the total number of students, which is 74, results in a mean of 69.55 marks.

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