25 Primary 2 students and 19 of Primary 3 students went on a school excursion. The number of Primary 3 girls was 3 times the number of Primary 2 girls, and there were 18 more Primary 2 boys than Primary 3 boys. How many more Primary 3 girls than Primary 3 boys went on the school excursion?
| Primary 2 |
Primary 3 |
| 25 |
19 |
| Girls |
Boys |
Girls |
Boys |
| 1 u |
1 p + 18 |
3 u |
1 p |
Total number of students in Primary 2 = 1 u + 1 p + 18
1 u + 1 p + 18 = 25
1 u + 1 p = 25 - 18
1 u + 1 p = 7 --- (1)
Total number of students in Primary 3 = 3 u + 1 p
3 u + 1 p = 19 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 19 - 7
3 u - 1 u = 12
2 u = 12
1 u = 12 ÷ 2 = 6
Number of girls in Primary 3
= 3 u
= 3 x 6
= 18
Number of boys in Primary 3
= 1 p
= 19 - 3 u
= 19 - 18
= 1
Number of more girls than boys in Primary 3
= 18 - 1
= 17
Answer(s): 17
