Fill in the blanks.
The ratio of the number of girls to the number of boys in Class A is 5 : 4.
The ratio of the number of girls to the number of boys in Class B is 4 : 5.
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 |
5 x 4 |
4 x 4 |
4 x 5 |
5 x 5 |
20 u |
16 u |
20 u |
25 u |
(a)
Change ratio into units.
The number of girls in Class A and Class B is the same.
LCM of 5 and 4 = 20
Class A
Girls : Boys
5 : 4
(x4) 20 : 16
Class B
Girls : Boys
4 : 5
(x5) 20 : 25
Number of girls in Class A = 20 u
(b)
Number of boys in Class B = 25 u
(c)
Number of children in Class B
= 20 u + 25 u
= 45 u
(d)
Number of children in Class A
= 20 u + 16 u
= 36 u
Total number of children
= 45 u + 36 u
= 81 u
Answer(s): (a) 20; (b) 25; (c) 45; (d) 81