Fill in the blanks.
The ratio of the number of boys to the number of girls in Class A is 3 : 1.
The ratio of the number of boys to the number of girls in Class B is 7 : 9.
The number of boys is the same.
- Number of boys in Class A = _____ u
- Number of girls in Class B = _____ u
- Number of children in Class B = _____ u
- Total number of children = _____ u
Class A |
Class B |
Boys |
Girls |
Boys |
Girls |
3 x 7 |
1 x 7 |
7 x 3 |
9 x 3 |
21 u |
7 u |
21 u |
27 u |
(a)
Change ratio into units.
The number of boys in Class A and Class B is the same.
LCM of 3 and 7 = 21
Class A
Boys : Girls
3 : 1
(x7) 21 : 7
Class B
Boys : Girls
7 : 9
(x3) 21 : 27
Number of boys in Class A = 21 u
(b)
Number of girls in Class B = 27 u
(c)
Number of children in Class B
= 21 u + 27 u
= 48 u
(d)
Number of children in Class A
= 21 u + 7 u
= 28 u
Total number of children
= 48 u + 28 u
= 76 u
Answer(s): (a) 21; (b) 27; (c) 48; (d) 76