PSLE Tim had a total of 150 coins in his coin box.
710 of all the coins saved were one-dollar coins. There were 3 times as many one-dollar coins as twenty-cent coins. The remaining coins were fifty-cent coins. What was the total value of all the coins in his coin box?
|
One-dollar |
Twenty-cent |
Fifty-cent |
Total |
Comparison between the number of 3 types of coins |
7x3 21 u |
3x3 9 u |
10x3 30 u
|
Comparison between the number of one-dollar and twenty-cent coins |
3x7 |
1x7 |
|
|
Number |
21 u |
7 u |
2 u |
30 u |
Value |
1 |
0.2 |
0.5 |
|
Number x value |
21 u |
1.4 u |
1 u |
23.4 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 7 and 3 = 21
Total number of coins = 30 u
30 u = 150
1 u = 150 ÷ 30 = 5
Total value of coins
= 21 u 1.4 u 1 u
= 23.4 u
= 23.4 x 5
= $117
Answer(s): $117