Question

Amber's mean mark on five tests is 80.

Her marks on four of these tests are 68, 81, 74 and 89.
Work out her mark on the fifth test.

Answer 1

88

Explanation:

The mean is the total sum of all the marks divided by how many there are.

68+81+74+89=312 Total of 4 tests

80×5 = 400 Total marks on 5 tests

400-312 = 88 Total marks on 5 tests - Total marks on 4 tests = 1 test

68+81+74+89+88 = 400

Answer 2

The answer is 88.

Explanation:

68+81+74+89+x/5=80

312+x/5=80

312+x=80*5

312+x=400

x=400-312

x=88