In March, Mary and Oliver had erasers in the ratio 13 : 7. In April, each of them gave away the same number of erasers. Mary then had four times as many erasers as Oliver.
- Find the ratio of the number of erasers Oliver had in March to the number of erasers he had in April.
- Find the ratio of the total number of erasers both had in March to the total number of erasers both had in April.
| |
Mary |
Oliver |
Difference |
| Before |
13x1 =
13 u |
7x1 =
7 u |
6x1 =
6 u |
| Change |
- 5 u |
- 5 u |
|
| After |
4x2 =
8 u |
1x2 =
2 u |
3x2 =
6 u |
(a)
Since Mary and Oliver gave away the same number of erasers, the difference in the number of erasers between Mary and Oliver at first and in the end remains the same.
Make the difference in the number of erasers at first and in the end the same. LCM of 6 and 3 is 6.
Oliver's erasers in March : Oliver's erasers in April
7 : 2
(b)
Total number of erasers in March
= 13 u + 7 u
= 20 u
Total number of erasers in April
= 8 u + 2 u
= 10 u
Total erasers in March : Total erasers in April
20 : 10
(÷10)2 : 1
Answer(s): (a) 7 : 2; (b) 2 : 1
