PSLE
Archie and Paul have the same total number of coins. Archie has a number of fifty-cent coins and 31 twenty-cent coins. The total mass of his coins is 1.253 kg. Paul has a number of fifty-cent coins and 71 twenty-cent coins.

1. Who has less money in coins? How much less? Give your answers in this format. (Eg Adam, $12)
2. Each fifty-cent coin is 2.8 g heavier than each twenty-cent coin. What is the total mass of Paul's coins in kg?

(a)
Both boys have the same number of coins. Since Paul has more twenty-cent coins than Archie, it means that Paul has less fifty-cent coins than Archie.  So Paul has less money.

Difference in the number of twenty-cent coins.
= 71 - 31
= 40

Difference in the value of 1 twenty-cent coin and 1 fifty-cent coin
= 50 - 20
= 30¢

Amount that Paul had less than Archie
= 40 x 30
= 1200¢
= $12

(b)
Difference in the mass between 40 twenty-cent coins and 40 fifty-cent coins
= 40 x 2.8
= 112 g
= 0.112 kg

Total mass of Paul's coins
= 1.253 - 0.112
= 1.141 kg

Answer(s): (a) Archie, $12; (b) 1.141 kg