Multiple choice

The following table shows the marks obtained by 140 students in an examination.

Marks 0 - 10 10 - 20 20 - 30 30 - 40 40 - 50
Number of students 20 24 40 36 20

Find the mean marks.

  1. 25

  2. 25.86

  3. 31.20

  4. 24.38
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Marks (classes) 0-10 10-20 20-30 30-40 40-50 Total
Class mark (xi) 5 15 25 35 45  
Frequency (fi) 20 24 40 36 20 140
fixi 100 360 1000 1260 900 3620

Mean $\bar x = \frac{total f_i x_i}{total f_i}$= 3620/140 = 25.86.

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