39 Primary 2 students and 35 of Primary 3 students went on a school camp. 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 camp?
Primary 2 |
Primary 3 |
39 |
35 |
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 = 39
1 u + 1 p = 39 - 18
1 u + 1 p = 21 --- (1)
Total number of students in Primary 3 = 3 u + 1 p
3 u + 1 p = 35 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 35 - 21
3 u - 1 u = 14
2 u = 14
1 u = 14 ÷ 2 = 7
Number of girls in Primary 3
= 3 u
= 3 x 7
= 21
Number of boys in Primary 3
= 1 p
= 35 - 3 u
= 35 - 21
= 14
Number of more girls than boys in Primary 3
= 21 - 14
= 7
Answer(s): 7