Question

In a series of tests, A appeared for 8 tests. Each test was marked out of 30 and averages 25. However, while checking his files, A could only find 7 of the 8 tests. For these, he scored 29, 26, 18, 20, 27, 24 and 29.
Determine how many marks he scored for the eighth test.

Answer 1

Total number of tests = 8

The average score of A = 25

Let the score of the 8^th test be x.

Then, total score of 8 tests = 29 + 26 + 18 + 20 + 27 + 24 + 29 + x

Now, we have
Mean = `"Total score of 8 tests"/"Total number of tests"`

⇒ 25 = `[ 29 + 26 + 18 + 20 + 27 + 24 + 29 + x ]/8`

⇒ 25 x 8 = 173 + x

⇒ x + 173 = 200

⇒ x = 200 - 173

⇒ x = 27

Thus, A scored 27 marks in the eights test.