PSLE
Oscar and Warren have the same total number of coins. Oscar has a number of twenty-cent coins and 60 five-cent coins. The total mass of his coins is 0.627 kg. Warren has a number of twenty-cent coins and 80 five-cent coins.

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

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

Difference in the number of five-cent coins.
= 80 - 60
= 20

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

Amount that Warren had less than Oscar
= 20 x 15
= 300¢
= $3

(b)
Difference in the mass between 20 five-cent coins and 20 twenty-cent coins
= 20 x 2.8
= 56 g
= 0.056 kg

Total mass of Warren's coins
= 0.627 - 0.056
= 0.571 kg

Answer(s): (a) Oscar, $3; (b) 0.571 kg