Fill in the blanks.
The ratio of the number of girls to the number of boys in Class A is 7 : 5.
The ratio of the number of girls to the number of boys in Class B is 4 : 7.
The number of girls is the same.
- Number of girls in Class A = _____ u
- Number of boys in Class B = _____ u
- Number of children in Class B = _____ u
- Total number of children = _____ u
Class A |
Class B |
Girls |
Boys |
Girls |
Boys |
7 x 4 |
5 x 4 |
4 x 7 |
7 x 7 |
28 u |
20 u |
28 u |
49 u |
(a)
Change ratio into units.
The number of girls in Class A and Class B is the same.
LCM of 7 and 4 = 28
Class A
Girls : Boys
7 : 5
(x4) 28 : 20
Class B
Girls : Boys
4 : 7
(x7) 28 : 49
Number of girls in Class A = 28 u
(b)
Number of boys in Class B = 49 u
(c)
Number of children in Class B
= 28 u + 49 u
= 77 u
(d)
Number of children in Class A
= 28 u + 20 u
= 48 u
Total number of children
= 77 u + 48 u
= 125 u
Answer(s): (a) 28; (b) 49; (c) 77; (d) 125