Question

a student aimed to get a mean mark of 80% in his mathematics test after 9 tests his mean mark is 79%. Calculate the lowest mark he requires in his last test to enable him to achieve his target.

Answer 1

89

Explanation:

construct the formula to obtain the total of marks in first 9 tests:

79 = x/9

79 * 9 = 711

x = 711

so to get 80% in the next test we construct this formula:

80 = 711 + y / 9 + 1

the value we get for y is 89

to confirm the answer, 711+89/10 gives us 80, which is the correct value we want