Question

Forty students have completed a math test. The mean score was 60 and a mean absolute deviation was 12. The teacher has decided to adjust the scores by adding 5 points to each test score. Calculate the new mean and mean absolute deviation.

Answer 1

The new mean would be 65, the deviation becomes 7

Explanation:

We can show a mock exam result below with prior mean of 60

Showing 12 students instead of 40 as the same rate would change if 40 students totaled 60 mean than those with same mean as 12 students.

42 45 49 51 55 56 63 64 68 72 73 86

mean total =724/ 12 = 60.33

We add 5 to each test score

47 50 54 56 60 61 68 69 73 77 78 91

mean total = 784 /12 =65.33

The mean just increases at same rate.