PSLE Sam and David have the same total number of coins. Sam has a number of fifty-cent coins and 34 twenty-cent coins. The total mass of his coins is 1.268 kg. David has a number of fifty-cent coins and 54 twenty-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 3.7 g heavier than each twenty-cent coin. What is the total mass of David's coins in kg?
(a)
Since Sam has less twenty-cent coins than David but both had the same number of coins, Sam had more money.
Both boys have the same number of coins. Since Sam has less twenty-cent coins than David, it means that Sam has more fifty-cent coins than David. So Sam has more money.
Difference in the number of twenty-cent coins.
= 54 - 34
= 20
Difference in the value of 1 twenty-cent coin and 1 fifty-cent coin
= 50 - 20
= 30¢
Amount that Sam had more than David
= 20 x 30
= 600¢
= $6
(b)
Difference in the mass between 20 twenty-cent coins and 20 fifty-cent coins
= 20 x 3.7
= 74 g
= 0.074 kg
Total mass of David's coins
= 1.268 - 0.074
= 1.194 kg
Answer(s): (a) Sam, $6; (b) 1.194 kg