PSLE
Archie and Riordan have the same total number of coins. Archie has a number of ten-cent coins and 52 five-cent coins. The total mass of his coins is 1.058 kg. Riordan has a number of ten-cent coins and 92 five-cent coins.

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

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

Both boys have the same number of coins. Since Archie has less five-cent coins than Riordan, it means that Archie has more ten-cent coins than Riordan. So Archie has more money.

Difference in the number of five-cent coins.
= 92 - 52
= 40

Difference in the value of 1 five-cent coin and 1 ten-cent coin
= 10 - 5
= 5¢

Amount that Archie had more than Riordan
= 40 x 5
= 200¢
= $2

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

Total mass of Riordan's coins
= 1.058 - 0.1
= 0.958 kg

Answer(s): (a) Archie, $2; (b) 0.958 kg