PSLE The number of girls and boys taking part in a quiz are in the ratio 1 : 7. These students are put into two teams. 50% of the girls and 10% of the boys are in Team B. The rest of the students are in Team C.
- What is the ratio of the number of students in Team C to Team B? Give your answer in the simplest form.
- The number of boys in Team B is more than 40. What is the smallest possible total number of students taking part in the quiz?
Girls |
Boys |
10 u |
70 u |
Team B |
Team C |
Team B |
Team C |
5 u |
5 u |
7 u |
63 u |
(a)
Girls : Boys
1 : 7
10 : 70
Number of girls in Team B
= 50% x 10 u
=
50100 x 10 u
= 5 u
Number of girls in Team C
= 10 u - 5 u
= 5 u
Number of boys in Team B
= 10% x 70 u
=
10100 x 70 u
= 7 u
Number of boys in Team C
= 70 u - 7 u
= 63 u
Team B : Team C
5 + 63 : 5 + 7
68 : 12
(÷4)17 : 3
(b)
Number of boys in Team B = 7 u
Since the number of boys in Team B is 7 u, it must be multiple of 7.
Number of sets of 7
= 40 ÷ 7
= 5 r 5
Since the number of boys in Team B is more than 40, the number of sets must be 1 more than 5.
1 u = 5 + 1 = 6
Smallest possible number of students
= 10 u + 70 u
= 80 u
= 80 x 6
= 480
Answer(s): (a) 17 : 3; (b) 480