Wendy saved two coins every day from Monday to Sunday by putting them into a coin box. Each coin was either a 10¢ or 50¢ coin. The total value of the coins at the end of 6 weeks was $17.20. How many of the coins were 50¢ coins?
| 50¢ |
Value of 50¢ |
10¢ |
Value of 10¢ |
Total value |
84
|
84 x 50¢ =
4200¢ |
0 |
0 x 10¢ =
0 |
4200¢ |
83
|
83 x 50¢ =
4150¢ |
1 |
1 x 10¢ =
10¢ |
4160¢ |
22
|
22 x 50¢ =
1100¢ |
62
|
62 x 10¢ =
620¢ |
1720¢ |
$1 = 100¢
$17.20 = 1720¢
Number of coins in one week
= 2 x 7
= 14
Number of coins in 6 weeks
= 6 x 14
= 84
Total amount saved if all the coins were 50¢
= 84 x 50
= 4200¢
Big difference between the total values of 50¢ coins and 10¢ coins
= 4200 - 1720
= 2480¢
Small difference between the value of one 50¢ coin and one 10¢ coin
= 50 - 10
= 40¢
Number of 10¢ coins
= 2480 ÷ 40
= 62
Number of 50¢ coins
= 84 - 62
= 22
Answer(s): 22
