Grace, Josiah, Joseph and Olivia share the same hobby of collecting erasers. The average number of erasers collected by the 4 friends is 27. Josiah collected 7 more erasers than Joseph but 15 fewer erasers than Grace. Olivia collected 5 erasers fewer than Joseph. Find the average number of erasers collected by Josiah, Joseph and Olivia. Round off your answer to the nearest whole number.
Number of erasers Joseph collected = 1 u
Number of erasers Josiah collected = 1 u + 7
Number of erasers Grace collected = 1 u + 7 + 15 = 1 u + 22
Number of erasers Olivia collected = 1 u - 5

Total number of erasers collected
= 4 x 27
= 108

Total number of erasers collected in units
= 1 u + 1 u + 7 + 1 u + 22 + 1 u - 5
= 4 u + 24

4 u + 24 = 108
4 u = 108 - 24 = 84

1 u = 84 ÷ 4 = 21

Total number of erasers collected by Josiah, Joseph and Olivia
= 1 u + 7 + 1 u + 1 u - 5
= 3 u + 2
= 3 x 21 + 2
= 65

Average number of erasers collected by Josiah, Joseph and Olivia
= 65 ÷ 3
≈ 22 (Round off to the nearest whole number.)

Answer(s): 22