Question

To gain a pass a student needs to achieve a mean of at least 60% in eight tests. In the first seven

tests the student achieved a mean of 54%. What percentage must the student achieve in test eight
if they are to pass the course?

Answer 1

Explanation:

the mean value is the sum of all data points divided by the number of data points.

first we have 7 tests and their mean value :

(t1 + t2 + t3 + t4 + t5 + t6 + t7) / 7 = 54

that means

(t1 + t2 + t3 + t4 + t5 + t6 + t7) = 54 × 7 = 378

in order for the mean value to be at least 60% after 8 tests, we need to add a t8, so that

(t1 + t2 + t3 + t4 + t5 + t6 + t7 + t8) = 60 × 8 = 480

because only then we have

(t1 + t2 + t3 + t4 + t5 + t6 + t7 + t8) / 8 = 60

and the student passes.

so,

(t1 + t2 + t3 + t4 + t5 + t6 + t7) + t8 = 480

378 + t8 = 480

t8 = 480 - 378 = 102%

the student would have to achieve 102% on the 8th test.

which would be normally impossible, but maybe the tests involve some bonus points.