Shannon 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 $14.80. 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¢ |
16
|
16 x 50¢ = 800¢ |
68
|
68 x 10¢ = 680¢ |
1480¢ |
$1 = 100¢
$14.80 = 1480¢
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 - 1480
= 2720¢
Small difference between the value of one 50¢ coin and one 10¢ coin
= 50 - 10
= 40¢
Number of 10¢ coins
= 2720 ÷ 40
= 68
Number of 50¢ coins
= 84 - 68
= 16
Answer(s): 16