28 Primary 2 students and 25 of Primary 3 students went on a school excursion. The number of Primary 3 girls was 4 times the number of Primary 2 girls, and there were 18 more Primary 2 boys than Primary 3 boys. How many more Primary 3 girls than Primary 3 boys went on the school excursion?
Primary 2 |
Primary 3 |
28 |
25 |
Girls |
Boys |
Girls |
Boys |
1 u |
1 p + 18 |
4 u |
1 p |
Total number of students in Primary 2 = 1 u + 1 p + 18
1 u + 1 p + 18 = 28
1 u + 1 p = 28 - 18
1 u + 1 p = 10 --- (1)
Total number of students in Primary 3 = 4 u + 1 p
4 u + 1 p = 25 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 25 - 10
4 u - 1 u = 15
3 u = 15
1 u = 15 ÷ 3 = 5
Number of girls in Primary 3
= 4 u
= 4 x 5
= 20
Number of boys in Primary 3
= 1 p
= 25 - 4 u
= 25 - 20
= 5
Number of more girls than boys in Primary 3
= 20 - 5
= 15
Answer(s): 15