PSLE Tim saved a total of $45 in coins in his coin box.
512 of all the coins saved were one-dollar coins. There were 2 times as many one-dollar coins as ten-cent coins. The remaining coins were fifty-cent coins. How many coins did Tim save in his coin box altogether?
|
One-dollar |
Ten-cent |
Fifty-cent |
Total |
Comparison between the number of 3 types of coins |
5x2 10 u |
7x2 14 u |
12x2 24 u
|
Comparison between the number of one-dollar and ten-cent coins |
2x5 |
1x5 |
|
|
Number |
10 u |
5 u |
9 u |
24 u |
Value |
1 |
0.1 |
0.5 |
|
Number x value |
10 u |
0.5 u |
4.5 u |
15 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 5 and 2 = 10
Total value of coins = 15 u
15 u = 45
1 u = 45 ÷ 15 = 3
Total number of coins
= 10 u + 5 u + 9 u
= 24 u
= 24 x 3
= 72
Answer(s): 72