PSLE Tommy and John have the same total number of coins. Tommy has a number of fifty-cent coins and 60 five-cent coins. The total mass of his coins is 0.532 kg. John has a number of fifty-cent coins and 80 five-cent coins.
- Who has more money in coins? How much more? Give your answers in this format. (Eg Adam, $12)
- Each fifty-cent coin is 3.4 g heavier than each five-cent coin. What is the total mass of John's coins in kg?
(a)
Since Tommy has less five-cent coins than John but both had the same number of coins, Tommy had more money.
Both boys have the same number of coins. Since Tommy has less five-cent coins than John, it means that Tommy has more fifty-cent coins than John. So Tommy has more money.
Difference in the number of five-cent coins.
= 80 - 60
= 20
Difference in the value of 1 five-cent coin and 1 fifty-cent coin
= 50 - 5
= 45¢
Amount that Tommy had more than John
= 20 x 45
= 900¢
= $9
(b)
Difference in the mass between 20 five-cent coins and 20 fifty-cent coins
= 20 x 3.4
= 68 g
= 0.068 kg
Total mass of John's coins
= 0.532 - 0.068
= 0.464 kg
Answer(s): (a) Tommy, $9; (b) 0.464 kg