PSLE
Tom and Pierre have the same total number of coins. Tom has a number of fifty-cent coins and 50 ten-cent coins. The total mass of his coins is 0.767 kg. Pierre has a number of fifty-cent coins and 70 ten-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 1.3 g heavier than each ten-cent coin. What is the total mass of Pierre's coins in kg?

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

Difference in the number of ten-cent coins.
= 70 - 50
= 20

Difference in the value of 1 ten-cent coin and 1 fifty-cent coin
= 50 - 10
= 40¢

Amount that Pierre had less than Tom
= 20 x 40
= 800¢
= $8

(b)
Difference in the mass between 20 ten-cent coins and 20 fifty-cent coins
= 20 x 1.3
= 26 g
= 0.026 kg

Total mass of Pierre's coins
= 0.767 - 0.026
= 0.741 kg

Answer(s): (a) Tom, $8; (b) 0.741 kg