Question

A teacher has given a test to a group of students. The set of scores is: 78, 79, 79, 81, and 83. Find the variance for this group of tests.

a. 2.24

b. 3.4

c. 5

d. 80


Can someone help me!?!?and also explain to me how you got the answer so I can understand it.

Answer 1

The variance is 3.2

Explanation:

step 1

Find the mean

[78+79+79+81+83]/5-------> 400/5------> 80

step 2

for each number: subtract the Mean and square the result

(78-80)²----->4

(79-80)²----> 1

(79-80)²----> 1

(81-80)²----> 1

(83-80)²----> 9

step 3

work out the mean of those squared differences

[4+1+1+1+9]/5-----> 16/5-----> 3.2----> this value is called the "Variance"