PSLE
Howard and Oscar have the same total number of coins. Howard has a number of twenty-cent coins and 30 five-cent coins. The total mass of his coins is 0.525 kg. Oscar has a number of twenty-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 twenty-cent coin is 2.3 g heavier than each five-cent coin. What is the total mass of Oscar's coins in kg?

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

Both boys have the same number of coins. Since Howard has less five-cent coins than Oscar, it means that Howard has more twenty-cent coins than Oscar. So Howard has more money.

Difference in the number of five-cent coins.
= 90 - 30
= 60

Difference in the value of 1 five-cent coin and 1 twenty-cent coin
= 20 - 5
= 15¢

Amount that Howard had more than Oscar
= 60 x 15
= 900¢
= $9

(b)
Difference in the mass between 60 five-cent coins and 60 twenty-cent coins
= 60 x 2.3
= 138 g
= 0.138 kg

Total mass of Oscar's coins
= 0.525 - 0.138
= 0.387 kg

Answer(s): (a) Howard, $9; (b) 0.387 kg