41 Primary 5 pupils and 33 of Primary 6 pupils went on a school camp. The number of Primary 6 boys was 3 times the number of Primary 5 boys, and there were 20 more Primary 5 girls than Primary 6 girls. How many less Primary 6 girls than Primary 6 boys went on the school camp?
| Primary 5 |
Primary 6 |
| 41 |
33 |
| Boys |
Girls |
Boys |
Girls |
| 1 u |
1 p + 20 |
3 u |
1 p |
Total number of pupils in Primary 5 = 1 u + 1 p + 20
1 u + 1 p + 20 = 41
1 u + 1 p = 41 - 20
1 u + 1 p = 21 --- (1)
Total number of pupils in Primary 6 = 3 u + 1 p
3 u + 1 p = 33 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 33 - 21
3 u - 1 u = 12
2 u = 12
1 u = 12 ÷ 2 = 6
Number of boys in Primary 6
= 3 u
= 3 x 6
= 18
Number of girls in Primary 6
= 1 p
= 33 - 3 u
= 33 - 18
= 15
Number of less girls than boys in Primary 6
= 18 - 15
= 3
Answer(s): 3
