PSLE Riordan and Flynn have the same total number of coins. Riordan has a number of fifty-cent coins and 70 twenty-cent coins. The total mass of his coins is 0.745 kg. Flynn has a number of fifty-cent coins and 130 twenty-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 2.5 g heavier than each twenty-cent coin. What is the total mass of Flynn's coins in kg?
(a)
Both boys have the same number of coins. Since Flynn has more twenty-cent coins than Riordan, it means that Flynn has less fifty-cent coins than Riordan. So Flynn has less money.
Difference in the number of twenty-cent coins.
= 130 - 70
= 60
Difference in the value of 1 twenty-cent coin and 1 fifty-cent coin
= 50 - 20
= 30¢
Amount that Flynn had less than Riordan
= 60 x 30
= 1800¢
= $18
(b)
Difference in the mass between 60 twenty-cent coins and 60 fifty-cent coins
= 60 x 2.5
= 150 g
= 0.15 kg
Total mass of Flynn's coins
= 0.745 - 0.15
= 0.595 kg
Answer(s): (a) Riordan, $18; (b) 0.595 kg