28 Primary 5 pupils and 25 of Primary 6 pupils went on a school oversea trip. The number of Primary 6 girls was 4 times the number of Primary 5 girls, and there were 15 more Primary 5 boys than Primary 6 boys. How many more Primary 6 girls than Primary 6 boys went on the school oversea trip?
Primary 5 |
Primary 6 |
28 |
25 |
Girls |
Boys |
Girls |
Boys |
1 u |
1 p + 15 |
4 u |
1 p |
Total number of pupils in Primary 5 = 1 u + 1 p + 15
1 u + 1 p + 15 = 28
1 u + 1 p = 28 - 15
1 u + 1 p = 13 --- (1)
Total number of pupils in Primary 6 = 4 u + 1 p
4 u + 1 p = 25 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 25 - 13
4 u - 1 u = 12
3 u = 12
1 u = 12 ÷ 3 = 4
Number of girls in Primary 6
= 4 u
= 4 x 4
= 16
Number of boys in Primary 6
= 1 p
= 25 - 4 u
= 25 - 16
= 9
Number of more girls than boys in Primary 6
= 16 - 9
= 7
Answer(s): 7