The number of girls to the number of boys in Primary 2 Love was 3 : 5. The number of girls to the number of boys in Primary 2 Faithfulness was 5 : 6. Both classes had the same number of girls. When 10 boys from Primary 2 Love joined Primary 2 Faithfulness, the ratio of the number of girls to the number of boys in Primary 2 Love became 3 : 4. Find the total enrolment of both classes.
Primary 2 Love |
Primary 2 Faithfulness |
Girls |
Boys |
Girls |
Boys |
3x5 |
5x5 |
5x3 |
6x3 |
1x15 |
|
1x15 |
|
15 u |
25 u |
15 u |
18 u |
The number of girls in both classes is the same. Make the number of girls the same. LCM of 3 and 5 is 15.
|
Primary 2 Love |
Primary 2 Faithfulness |
|
Girls |
Boys |
Girls |
Boys |
Before |
15 u |
25 u |
15 u |
18 u |
Change |
|
- 10 |
|
+ 10 |
After |
3x5 = 15 u |
4x5 = 20 u |
15 u |
18 u + 10 |
The number of girls in Primary 2 Love remains unchanged. Make the number of girls in Primary 2 the same. LCM of 15 and 3 is 15.
Number of boys from Primary 2 Love that joined Primary 2 Faithfulness
= 25 u - 20 u
= 5 u
5 u = 10
1 u = 10 ÷ 5 = 2
Total enrolment of both classes
= 15 u + 25 u + 15 u + 18 u
= 73 u
= 73 x 2
= 146
Answer(s): 146