18 Primary 5 students and 12 of Primary 6 students went on a school camp. The number of Primary 6 girls was 4 times the number of Primary 5 girls, and there were 12 less Primary 6 boys than Primary 5 boys. How many less Primary 6 boys than Primary 6 girls went on the school camp?
Primary 5 |
Primary 6 |
18 |
12 |
Girls |
Boys |
Girls |
Boys |
1 u |
1 p + 12 |
4 u |
1 p |
Total number of students in Primary 5 = 1 u + 1 p + 12
1 u + 1 p + 12 = 18
1 u + 1 p = 18 - 12
1 u + 1 p = 6 --- (1)
Total number of students in Primary 6 = 4 u + 1 p
4 u + 1 p = 12 --- (2)
(2) - (1)
(4 u + 1 p) - (1 u + 1 p) = 12 - 6
4 u - 1 u = 6
3 u = 6
1 u = 6 ÷ 3 = 2
Number of girls in Primary 6
= 4 u
= 4 x 2
= 8
Number of boys in Primary 6
= 1 p
= 12 - 4 u
= 12 - 8
= 4
Number of less boys than girls in Primary 6
= 8 - 4
= 4
Answer(s): 4