20 Primary 5 pupils and 17 of Primary 6 pupils went on a school oversea trip. The number of Primary 6 boys was 3 times the number of Primary 5 boys, and there were 9 more Primary 5 girls than Primary 6 girls. How many more Primary 6 boys than Primary 6 girls went on the school oversea trip?
| Primary 5 |
Primary 6 |
| 20 |
17 |
| Boys |
Girls |
Boys |
Girls |
| 1 u |
1 p + 9 |
3 u |
1 p |
Total number of pupils in Primary 5 = 1 u + 1 p + 9
1 u + 1 p + 9 = 20
1 u + 1 p = 20 - 9
1 u + 1 p = 11 --- (1)
Total number of pupils in Primary 6 = 3 u + 1 p
3 u + 1 p = 17 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 17 - 11
3 u - 1 u = 6
2 u = 6
1 u = 6 ÷ 2 = 3
Number of boys in Primary 6
= 3 u
= 3 x 3
= 9
Number of girls in Primary 6
= 1 p
= 17 - 3 u
= 17 - 9
= 8
Number of more boys than girls in Primary 6
= 9 - 8
= 1
Answer(s): 1
