The data below shows the number of students in class A and B having secured different marks.
| Marks | Students in class A | Students in class B |
| 0-2 | 3 | 2 |
| 2-4 | 4 | 1 |
| 4-6 | 1 | 3 |
| 6-8 | 1 | 1 |
| 8-10 | 1 | 1 |
| 10-12 | 0 | 2 |
What is the combined mean of A and B?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 4.7.
| Understanding/Application |
|
Mean = Sum of total marks/Total students Mean of A = (1 × 3 + 3 × 4 + 5 × 1 + 7 × 1 + 9 × 1 + 11 × 0)/(3 + 4 + 1 + 1 + 1 + 0) = (3 + 12 + 5 + 7 + 9)/10 = 36/10 = 3.6 |
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Mean of B = (1 × 2 + 3 × 1 + 5 × 3 + 7 × 1 + 9 × 1 + 11 × 2)/(2 + 1 + 3 + 1 + 1 + 2) = (2 + 3 + 15 + 7 + 9 + 22)/10 = 58/10 = 5.8 Combined mean of A and B = (3.6 + 5.8)/2 = (9.4)/2 = 4.7 |