28 Primary 1 pupils and 23 of Primary 2 pupils went on a school camp. The number of Primary 2 girls was 4 times the number of Primary 1 girls, and there were 17 more Primary 1 boys than Primary 2 boys. How many more Primary 2 girls than Primary 2 boys went on the school camp?
Primary 1 |
Primary 2 |
28 |
23 |
Girls |
Boys |
Girls |
Boys |
1 u |
1 p + 17 |
4 u |
1 p |
Total number of pupils in Primary 1 = 1 u + 1 p + 17
1 u + 1 p + 17 = 28
1 u + 1 p = 28 - 17
1 u + 1 p = 11 --- (1)
Total number of pupils in Primary 2 = 4 u + 1 p
4 u + 1 p = 23 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 23 - 11
4 u - 1 u = 12
3 u = 12
1 u = 12 ÷ 3 = 4
Number of girls in Primary 2
= 4 u
= 4 x 4
= 16
Number of boys in Primary 2
= 1 p
= 23 - 4 u
= 23 - 16
= 7
Number of more girls than boys in Primary 2
= 16 - 7
= 9
Answer(s): 9