19 Primary 3 pupils and 13 of Primary 4 pupils went on a school outing. The number of Primary 4 girls was 4 times the number of Primary 3 girls, and there were 12 less Primary 4 boys than Primary 3 boys. How many less Primary 4 boys than Primary 4 girls went on the school outing?
| Primary 3 |
Primary 4 |
| 19 |
13 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 12 |
4 u |
1 p |
Total number of pupils in Primary 3 = 1 u + 1 p + 12
1 u + 1 p + 12 = 19
1 u + 1 p = 19 - 12
1 u + 1 p = 7 --- (1)
Total number of pupils in Primary 4 = 4 u + 1 p
4 u + 1 p = 13 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 13 - 7
4 u - 1 u = 6
3 u = 6
1 u = 6 ÷ 3 = 2
Number of girls in Primary 4
= 4 u
= 4 x 2
= 8
Number of boys in Primary 4
= 1 p
= 13 - 4 u
= 13 - 8
= 5
Number of less boys than girls in Primary 4
= 8 - 5
= 3
Answer(s): 3
