Tina saved two coins every day from Monday to Sunday by putting them into a tin can. Each coin was either a 10¢ or 50¢ coin. The total value of the coins at the end of 5 weeks was $18.60. 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¢ |
29
|
29 x 50¢ = 1450¢ |
41
|
41 x 10¢ = 410¢ |
1860¢ |
$1 = 100¢
$18.60 = 1860¢
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 - 1860
= 1640¢
Small difference between the value of one 50¢ coin and one 10¢ coin
= 50 - 10
= 40¢
Number of 10¢ coins
= 1640 ÷ 40
= 41
Number of 50¢ coins
= 70 - 41
= 29
Answer(s): 29