PSLE Fred kept his black and red beads in two boxes. The ratio of the number of black to red beads in the first box was 3 : 4 and it was 1 : 2 in the second box. The two boxes contained the same number of beads. What fraction of Fred's beads were black beads?
First box |
Second box |
1x21 21 u |
1x21 21 u |
7x3 |
3x7 |
Black |
Red |
Black |
Red |
3x3 |
4x3 |
1x7 |
2x7 |
9 u |
12 u |
7 u |
14 u |
The total number of beads in the first box and the second box is the same. Make the total number of beads in each box the same. LCM of 7 and 3 is 21.
Total number of black beads
= 9 u + 7 u
= 16 u
Total number of beads
= 21 u + 21 u
= 42 u
Fraction of Fred's beads that were black beads
=
1642 =
821 Answer(s):
821