Rachel saved two coins every day from Monday to Sunday by putting them into a piggy bank. Each coin was either a 5¢ or 50¢ coin. The total value of the coins at the end of 3 weeks was $17.40. How many of the coins were 50¢ coins?
| 50¢ |
Value of 50¢ |
5¢ |
Value of 5¢ |
Total value |
42
|
42 x 50¢ =
2100¢ |
0 |
0 x 5¢ =
0 |
2100¢ |
41
|
41 x 50¢ =
2050¢ |
1 |
1 x 5¢ =
5¢ |
2055¢ |
34
|
34 x 50¢ =
1700¢ |
8
|
8 x 5¢ =
40¢ |
1740¢ |
$1 = 100¢
$17.40 = 1740¢
Number of coins in one week
= 2 x 7
= 14
Number of coins in 3 weeks
= 3 x 14
= 42
Total amount saved if all the coins were 50¢
= 42 x 50
= 2100¢
Big difference between the total values of 50¢ coins and 5¢ coins
= 2100 - 1740
= 360¢
Small difference between the value of one 50¢ coin and one 5¢ coin
= 50 - 5
= 45¢
Number of 5¢ coins
= 360 ÷ 45
= 8
Number of 50¢ coins
= 42 - 8
= 34
Answer(s): 34
