PSLE
Zane and Oliver have the same total number of coins. Zane has a number of fifty-cent coins and 50 five-cent coins. The total mass of his coins is 0.847 kg. Oliver has a number of fifty-cent coins and 90 five-cent coins.

1. Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
2. Each fifty-cent coin is 2.5 g heavier than each five-cent coin. What is the total mass of Oliver's coins in kg?

(a)
Since Zane has less five-cent coins than Oliver but both had the same number of coins, Zane had more money.

Both boys have the same number of coins. Since Zane has less five-cent coins than Oliver, it means that Zane has more fifty-cent coins than Oliver. So Zane has more money.

Difference in the number of five-cent coins.
= 90 - 50
= 40

Difference in the value of 1 five-cent coin and 1 fifty-cent coin
= 50 - 5
= 45¢

Amount that Zane had more than Oliver
= 40 x 45
= 1800¢
= $18

(b)
Difference in the mass between 40 five-cent coins and 40 fifty-cent coins
= 40 x 2.5
= 100 g
= 0.1 kg

Total mass of Oliver's coins
= 0.847 - 0.1
= 0.747 kg

Answer(s): (a) Zane, $18; (b) 0.747 kg