35 Primary 5 pupils and 28 of Primary 6 pupils went on a school excursion. The number of Primary 6 boys was 3 times the number of Primary 5 boys, and there were 19 less Primary 6 girls than Primary 5 girls. How many less Primary 6 girls than Primary 6 boys went on the school excursion?
Primary 5 |
Primary 6 |
35 |
28 |
Boys |
Girls |
Boys |
Girls |
1 u |
1 p + 19 |
3 u |
1 p |
Total number of pupils in Primary 5 = 1 u + 1 p + 19
1 u + 1 p + 19 = 35
1 u + 1 p = 35 - 19
1 u + 1 p = 16 --- (1)
Total number of pupils in Primary 6 = 3 u + 1 p
3 u + 1 p = 28 --- (2)
(2) - (1)
(3 u + 1 p) - (1 u + 1 p) = 28 - 16
3 u - 1 u = 12
2 u = 12
1 u = 12 ÷ 2 = 6
Number of boys in Primary 6
= 3 u
= 3 x 6
= 18
Number of girls in Primary 6
= 1 p
= 28 - 3 u
= 28 - 18
= 10
Number of less girls than boys in Primary 6
= 18 - 10
= 8
Answer(s): 8