24 Primary 3 students and 16 of Primary 4 students went on a school oversea trip. The number of Primary 4 girls was 3 times the number of Primary 3 girls, and there were 18 more Primary 3 boys than Primary 4 boys. How many less Primary 4 boys than Primary 4 girls went on the school oversea trip?
| Primary 3 |
Primary 4 |
| 24 |
16 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 18 |
3 u |
1 p |
Total number of students in Primary 3 = 1 u + 1 p + 18
1 u + 1 p + 18 = 24
1 u + 1 p = 24 - 18
1 u + 1 p = 6 --- (1)
Total number of students in Primary 4 = 3 u + 1 p
3 u + 1 p = 16 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 16 - 6
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
= 16 - 3 u
= 16 - 15
= 1
Number of less boys than girls in Primary 4
= 15 - 1
= 14
Answer(s): 14
