PSLE Sean and Ken have the same total number of coins. Sean has a number of fifty-cent coins and 50 five-cent coins. The total mass of his coins is 0.858 kg. Ken has a number of fifty-cent coins and 70 five-cent coins.
- Who has less money in coins? How much less? Give your answers in this format. (Eg Adam, $12)
- Each fifty-cent coin is 1.2 g heavier than each five-cent coin. What is the total mass of Ken's coins in kg?
(a)
Both boys have the same number of coins. Since Ken has more five-cent coins than Sean, it means that Ken has less fifty-cent coins than Sean. So Ken has less money.
Difference in the number of five-cent coins.
= 70 - 50
= 20
Difference in the value of 1 five-cent coin and 1 fifty-cent coin
= 50 - 5
= 45¢
Amount that Ken had less than Sean
= 20 x 45
= 900¢
= $9
(b)
Difference in the mass between 20 five-cent coins and 20 fifty-cent coins
= 20 x 1.2
= 24 g
= 0.024 kg
Total mass of Ken's coins
= 0.858 - 0.024
= 0.834 kg
Answer(s): (a) Sean, $9; (b) 0.834 kg