26 Primary 1 pupils and 21 of Primary 2 pupils went on a school trip. The number of Primary 2 girls was 3 times the number of Primary 1 girls, and there were 15 more Primary 1 boys than Primary 2 boys. How many less Primary 2 boys than Primary 2 girls went on the school trip?
Primary 1 |
Primary 2 |
26 |
21 |
Girls |
Boys |
Girls |
Boys |
1 u |
1 p + 15 |
3 u |
1 p |
Total number of pupils in Primary 1 = 1 u + 1 p + 15
1 u + 1 p + 15 = 26
1 u + 1 p = 26 - 15
1 u + 1 p = 11 --- (1)
Total number of pupils in Primary 2 = 3 u + 1 p
3 u + 1 p = 21 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 21 - 11
3 u - 1 u = 10
2 u = 10
1 u = 10 ÷ 2 = 5
Number of girls in Primary 2
= 3 u
= 3 x 5
= 15
Number of boys in Primary 2
= 1 p
= 21 - 3 u
= 21 - 15
= 6
Number of less boys than girls in Primary 2
= 15 - 6
= 9
Answer(s): 9