PSLE Bobby kept his grey and red marbles in two boxes. The ratio of the number of grey to red marbles in the first box was 5 : 7 and it was 1 : 3 in the second box. The two boxes contained the same number of marbles. What fraction of Bobby's marbles were red marbles?
First box |
Second box |
1x12 12 u |
1x12 12 u |
12x1 |
4x3 |
Grey |
Red |
Grey |
Red |
5x1 |
7x1 |
1x3 |
3x3 |
5 u |
7 u |
3 u |
9 u |
The total number of marbles in the first box and the second box is the same. Make the total number of marbles in each box the same.
LCM of 12 and 4 is 12.
Total number of red marbles
= 7 u + 9 u
= 16 u
Total number of marbles
= 12 u + 12 u
= 24 u
Fraction of Bobby's marbles that were red marbles
=
1624 =
23 Answer(s):
23