38 Primary 3 pupils and 29 of Primary 4 pupils went on a school trip. The number of Primary 4 girls was 3 times the number of Primary 3 girls, and there were 19 less Primary 4 boys than Primary 3 boys. How many less Primary 4 boys than Primary 4 girls went on the school trip?
| Primary 3 |
Primary 4 |
| 38 |
29 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 19 |
3 u |
1 p |
Total number of pupils in Primary 3 = 1 u + 1 p + 19
1 u + 1 p + 19 = 38
1 u + 1 p = 38 - 19
1 u + 1 p = 19 --- (1)
Total number of pupils in Primary 4 = 3 u + 1 p
3 u + 1 p = 29 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 29 - 19
3 u - 1 u = 10
2 u = 10
1 u = 10 ÷ 2 = 5
Number of girls in Primary 4
= 3 u
= 3 x 5
= 15
Number of boys in Primary 4
= 1 p
= 29 - 3 u
= 29 - 15
= 14
Number of less boys than girls in Primary 4
= 15 - 14
= 1
Answer(s): 1
