PSLE Ahmad and Riordan have the same total number of coins. Ahmad has a number of fifty-cent coins and 46 ten-cent coins. The total mass of his coins is 0.729 kg. Riordan has a number of fifty-cent coins and 66 ten-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 2.1 g heavier than each ten-cent coin. What is the total mass of Riordan's coins in kg?
(a)
Since Ahmad has less ten-cent coins than Riordan but both had the same number of coins, Ahmad had more money.
Both boys have the same number of coins. Since Ahmad has less ten-cent coins than Riordan, it means that Ahmad has more fifty-cent coins than Riordan. So Ahmad has more money.
Difference in the number of ten-cent coins.
= 66 - 46
= 20
Difference in the value of 1 ten-cent coin and 1 fifty-cent coin
= 50 - 10
= 40¢
Amount that Ahmad had more than Riordan
= 20 x 40
= 800¢
= $8
(b)
Difference in the mass between 20 ten-cent coins and 20 fifty-cent coins
= 20 x 2.1
= 42 g
= 0.042 kg
Total mass of Riordan's coins
= 0.729 - 0.042
= 0.687 kg
Answer(s): (a) Ahmad, $8; (b) 0.687 kg