23 Primary 1 students and 16 of Primary 2 students went on a school trip. The number of Primary 2 girls was 3 times the number of Primary 1 girls, and there were 17 less Primary 2 boys than Primary 1 boys. How many less Primary 2 boys than Primary 2 girls went on the school trip?
| Primary 1 |
Primary 2 |
| 23 |
16 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 17 |
3 u |
1 p |
Total number of students in Primary 1 = 1 u + 1 p + 17
1 u + 1 p + 17 = 23
1 u + 1 p = 23 - 17
1 u + 1 p = 6 --- (1)
Total number of students in Primary 2 = 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 2
= 3 u
= 3 x 5
= 15
Number of boys in Primary 2
= 1 p
= 16 - 3 u
= 16 - 15
= 1
Number of less boys than girls in Primary 2
= 15 - 1
= 14
Answer(s): 14
