16 Primary 3 students and 13 of Primary 4 students went on a school outing. The number of Primary 4 boys was 3 times the number of Primary 3 boys, and there were 11 less Primary 4 girls than Primary 3 girls. How many less Primary 4 girls than Primary 4 boys went on the school outing?
| Primary 3 |
Primary 4 |
| 16 |
13 |
| Boys |
Girls |
Boys |
Girls |
| 1 u |
1 p + 11 |
3 u |
1 p |
Total number of students in Primary 3 = 1 u + 1 p + 11
1 u + 1 p + 11 = 16
1 u + 1 p = 16 - 11
1 u + 1 p = 5 --- (1)
Total number of students in Primary 4 = 3 u + 1 p
3 u + 1 p = 13 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 13 - 5
3 u - 1 u = 8
2 u = 8
1 u = 8 ÷ 2 = 4
Number of boys in Primary 4
= 3 u
= 3 x 4
= 12
Number of girls in Primary 4
= 1 p
= 13 - 3 u
= 13 - 12
= 1
Number of less girls than boys in Primary 4
= 12 - 1
= 11
Answer(s): 11
