Penelope saved two coins every day from Monday to Sunday by putting them into a glass jar. Each coin was either a 10¢ or 50¢ coin. The total value of the coins at the end of 5 weeks was $14.60. How many of the coins were 50¢ coins?
| 50¢ |
Value of 50¢ |
10¢ |
Value of 10¢ |
Total value |
70
|
70 x 50¢ =
3500¢ |
0 |
0 x 10¢ =
0 |
3500¢ |
69
|
69 x 50¢ =
3450¢ |
1 |
1 x 10¢ =
10¢ |
3460¢ |
19
|
19 x 50¢ =
950¢ |
51
|
51 x 10¢ =
510¢ |
1460¢ |
$1 = 100¢
$14.60 = 1460¢
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 10¢ coins
= 3500 - 1460
= 2040¢
Small difference between the value of one 50¢ coin and one 10¢ coin
= 50 - 10
= 40¢
Number of 10¢ coins
= 2040 ÷ 40
= 51
Number of 50¢ coins
= 70 - 51
= 19
Answer(s): 19
