Olivia saved two coins every day from Monday to Sunday by putting them into a coin box. Each coin was either a 5¢ or 50¢ coin. The total value of the coins at the end of 5 weeks was $13.40. How many of the coins were 50¢ coins?
50¢ |
Value of 50¢ |
5¢ |
Value of 5¢ |
Total value |
70
|
70 x 50¢ = 3500¢ |
0 |
0 x 5¢ = 0 |
3500¢ |
69
|
69 x 50¢ = 3450¢ |
1 |
1 x 5¢ = 5¢ |
3455¢ |
22
|
22 x 50¢ = 1100¢ |
48
|
48 x 5¢ = 240¢ |
1340¢ |
$1 = 100¢
$13.40 = 1340¢
Number of coins in one week
= 2 x 7
= 14
Number of coins in 5 weeks
= 5 x 14
= 70
Total amount saved if all the coins were 50¢
= 70 x 50
= 3500¢
Big difference between the total values of 50¢ coins and 5¢ coins
= 3500 - 1340
= 2160¢
Small difference between the value of one 50¢ coin and one 5¢ coin
= 50 - 5
= 45¢
Number of 5¢ coins
= 2160 ÷ 45
= 48
Number of 50¢ coins
= 70 - 48
= 22
Answer(s): 22