Fill in the blanks.
The ratio of the number of boys to the number of girls in Class A is 7 : 4.
The ratio of the number of boys to the number of girls in Class B is 4 : 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 |
7 x 4 |
4 x 4 |
4 x 7 |
9 x 7 |
28 u |
16 u |
28 u |
63 u |
(a)
Change ratio into units.
The number of boys in Class A and Class B is the same.
LCM of 7 and 4 = 28
Class A
Boys : Girls
7 : 4
(x4) 28 : 16
Class B
Boys : Girls
4 : 9
(x7) 28 : 63
Number of boys in Class A = 28 u
(b)
Number of girls in Class B = 63 u
(c)
Number of children in Class B
= 28 u + 63 u
= 91 u
(d)
Number of children in Class A
= 28 u + 16 u
= 44 u
Total number of children
= 91 u + 44 u
= 135 u
Answer(s): (a) 28; (b) 63; (c) 91; (d) 135