PSLE
Andy and Mark have the same total number of coins. Andy has a number of ten-cent coins and 70 five-cent coins. The total mass of his coins is 1.175 kg. Mark has a number of ten-cent coins and 110 five-cent coins.

1. Who has less money in coins? How much less? Give your answers in this format. (Eg Adam, $12)
2. Each ten-cent coin is 3.8 g heavier than each five-cent coin. What is the total mass of Mark's coins in kg?

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

Difference in the number of five-cent coins.
= 110 - 70
= 40

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

Amount that Mark had less than Andy
= 40 x 5
= 200¢
= $2

(b)
Difference in the mass between 40 five-cent coins and 40 ten-cent coins
= 40 x 3.8
= 152 g
= 0.152 kg

Total mass of Mark's coins
= 1.175 - 0.152
= 1.023 kg

Answer(s): (a) Andy, $2; (b) 1.023 kg