PSLE
Tim and David have the same total number of coins. Tim has a number of ten-cent coins and 35 five-cent coins. The total mass of his coins is 0.62 kg. David has a number of ten-cent coins and 55 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 2.4 g heavier than each five-cent coin. What is the total mass of David's coins in kg?

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

Difference in the number of five-cent coins.
= 55 - 35
= 20

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

Amount that David had less than Tim
= 20 x 5
= 100¢
= $1

(b)
Difference in the mass between 20 five-cent coins and 20 ten-cent coins
= 20 x 2.4
= 48 g
= 0.048 kg

Total mass of David's coins
= 0.62 - 0.048
= 0.572 kg

Answer(s): (a) Tim, $1; (b) 0.572 kg