22 Primary 3 students and 12 of Primary 4 students went on a school excursion. The number of Primary 4 boys was 3 times the number of Primary 3 boys, and there were 16 more Primary 3 girls than Primary 4 girls. How many less Primary 4 girls than Primary 4 boys went on the school excursion?
| Primary 3 |
Primary 4 |
| 22 |
12 |
| Boys |
Girls |
Boys |
Girls |
| 1 u |
1 p + 16 |
3 u |
1 p |
Total number of students in Primary 3 = 1 u + 1 p + 16
1 u + 1 p + 16 = 22
1 u + 1 p = 22 - 16
1 u + 1 p = 6 --- (1)
Total number of students in Primary 4 = 3 u + 1 p
3 u + 1 p = 12 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 12 - 6
3 u - 1 u = 6
2 u = 6
1 u = 6 ÷ 2 = 3
Number of boys in Primary 4
= 3 u
= 3 x 3
= 9
Number of girls in Primary 4
= 1 p
= 12 - 3 u
= 12 - 9
= 3
Number of less girls than boys in Primary 4
= 9 - 3
= 6
Answer(s): 6
