PSLE Jack kept his grey and black cards in two boxes. The ratio of the number of grey to black cards in the first box was 1 : 6 and it was 1 : 2 in the second box. The two boxes contained the same number of cards. What fraction of Jack's cards were grey cards?
First box |
Second box |
1x21 21 u |
1x21 21 u |
7x3 |
3x7 |
Grey |
Black |
Grey |
Black |
1x3 |
6x3 |
1x7 |
2x7 |
3 u |
18 u |
7 u |
14 u |
The total number of cards in the first box and the second box is the same. Make the total number of cards in each box the same. LCM of 7 and 3 is 21.
Total number of grey cards
= 3 u + 7 u
= 10 u
Total number of cards
= 21 u + 21 u
= 42 u
Fraction of Jack's cards that were grey cards
=
1042 =
521 Answer(s):
521