Martin earned the following scores on his last five tests. 98, 78, 84, 75, 91 what is the mean absolute deviation of his scores? 37.2 0 6.2 7.44 ? ?

in this exercise we have to calculate the averages of the scores so we have to:

A)85.2

B)7.44

First, let's calculate the average score as:

Find the difference between the average and each test score, after that we will calculate the total average of all grades then:

See more about averages at link

find the average of his scores:

98 +78+84 +75 +91 = 426/5 = 85.2

now find the difference between the average and each test score:

98 - 85.2 = 12.8

85.2 -78 = 7.2

85.2 - 84 = 1.2

85.2 -75 = 10.2

91-85.2 = 5.8

 total those and divide by the number of tests

12.8 + 7.2 + 1.2 +10.2 +5.8 =37.2/5 = 7.44