Fill in the blanks.
Number of boys at first is 70% of the children.
Number of boys is then decreased to 55% of the children.
- Number of boys at first = _____ u
- Number of boys in the end = _____ u
- Decrease in the number of boys = _____ u
- Number of children in the end = _____ u
|
Boys |
Girls |
Before |
7 x 3 = 21 u |
3 x 3 = 9 u |
Change |
- ? |
No change |
After |
11 x 1 = 11 u |
9 x 1 = 9 u |
(a)
Change percentage into units.
70% =
70100 =
71055% =
55100 =
1120 Fraction of the children who are girls at first
= 1 -
710=
310 Fraction of the children who are girls in the end
= 1 -
1120=
920Number of girls at first and in the end remains the same.
The number of girls is the unchanged quantity.
LCM of 3 and 9 = 9
Number of boys at first = 21 u
(b)
Number of boys in the end = 11 u
(c)
Decrease in the number of boys
= 21 u - 11 u
= 10 u
(d)
Number of children in the end
= 11 u + 9 u
= 20 u
Answer(s): (a) 21; (b) 11; (c) 10; (d) 20