28 Primary 4 students and 24 of Primary 5 students went on a school trip. The number of Primary 5 boys was 4 times the number of Primary 4 boys, and there were 19 less Primary 5 girls than Primary 4 girls. How many less Primary 5 girls than Primary 5 boys went on the school trip?
Primary 4 |
Primary 5 |
28 |
24 |
Boys |
Girls |
Boys |
Girls |
1 u |
1 p + 19 |
4 u |
1 p |
Total number of students in Primary 4 = 1 u + 1 p + 19
1 u + 1 p + 19 = 28
1 u + 1 p = 28 - 19
1 u + 1 p = 9 --- (1)
Total number of students in Primary 5 = 4 u + 1 p
4 u + 1 p = 24 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 24 - 9
4 u - 1 u = 15
3 u = 15
1 u = 15 ÷ 3 = 5
Number of boys in Primary 5
= 4 u
= 4 x 5
= 20
Number of girls in Primary 5
= 1 p
= 24 - 4 u
= 24 - 20
= 4
Number of less girls than boys in Primary 5
= 20 - 4
= 16
Answer(s): 16