Nathan, Joseph, Elijah and Isaiah share the same hobby of collecting stickers. The average number of stickers collected by the 4 friends is 24. Joseph collected 7 more stickers than Elijah but 15 fewer stickers than Nathan. Isaiah collected 5 stickers fewer than Elijah. Find the average number of stickers collected by Joseph, Elijah and Isaiah. Round off your answer to the nearest whole number.
Number of stickers Elijah collected = 1 u
Number of stickers Joseph collected = 1 u + 7
Number of stickers Nathan collected = 1 u + 7 + 15 = 1 u + 22
Number of stickers Isaiah collected = 1 u - 5

Total number of stickers collected
= 4 x 24
= 96

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

4 u + 24 = 96
4 u = 96 - 24 = 72

1 u = 72 ÷ 4 = 18

Total number of stickers collected by Joseph, Elijah and Isaiah
= 1 u + 7 + 1 u + 1 u - 5
= 3 u + 2
= 3 x 18 + 2
= 56

Average number of stickers collected by Joseph, Elijah and Isaiah
= 56 ÷ 3
≈ 19 (Round off to the nearest whole number.)

Answer(s): 19