PSLE David had a total of 480 coins in his coin box.
512 of all the coins saved were one-dollar coins. There were 4 times as many one-dollar coins as ten-cent coins. The remaining coins were twenty-cent coins. What was the total value of all the coins in his coin box?
|
One-dollar |
Ten-cent |
Twenty-cent |
Total |
Comparison between the number of 3 types of coins |
5x4 20 u |
7x4 28 u |
12x4 48 u
|
Comparison between the number of one-dollar and ten-cent coins |
4x5 |
1x5 |
|
|
Number |
20 u |
5 u |
23 u |
48 u |
Value |
1 |
0.1 |
0.2 |
|
Number x value |
20 u |
0.5 u |
4.6 u |
25.1 u |
Number of $1 coins is the repeated identity.
Make the number of $1 coins the same.
LCM of 5 and 4 = 20
Total number of coins = 48 u
48 u = 480
1 u = 480 ÷ 48 = 10
Total value of coins
= 20 u 0.5 u 4.6 u
= 25.1 u
= 25.1 x 10
= $251
Answer(s): $251