PSLE Fred saved a total of $29 in coins in his coin box.
47 of all the coins saved were one-dollar coins. There were 3 times as many one-dollar coins as fifty-cent coins. The remaining coins were ten-cent coins. How many coins did Fred save in his coin box altogether?
|
One-dollar |
Fifty-cent |
Ten-cent |
Total |
Comparison between the number of 3 types of coins |
4x3 12 u |
3x3 9 u |
7x3 21 u
|
Comparison between the number of one-dollar and fifty-cent coins |
3x4 |
1x4 |
|
|
Number |
12 u |
4 u |
5 u |
21 u |
Value |
1 |
0.5 |
0.1 |
|
Number x value |
12 u |
2 u |
0.5 u |
14.5 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 4 and 3 = 12
Total value of coins = 14.5 u
14.5 u = 29
1 u = 29 ÷ 14.5 = 2
Total number of coins
= 12 u + 4 u + 5 u
= 21 u
= 21 x 2
= 42
Answer(s): 42