PSLE Tom had blue notebooks and orange notebooks for sale. He sold 20 blue notebooks. 60% of the notebooks sold were orange.
- How many blue notebooks and orange notebooks did Tom sell altogether?
- He sold 50% of his notebooks. 60% of the notebooks left unsold were blue. How many orange notebooks did Tom have at first?
| |
Blue |
Orange |
Total |
Total in percent |
| Before |
5 u |
5 u |
10 u |
100% |
| Change |
- 40%
- 2 u |
- 60%
- 3 u |
- 100%
- 5 u |
- 50% |
| After |
60%
3 u |
40%
2 u |
100%
5 u |
50%
|
60% =
60100 =
35 Total number of notebooks sold = 5 u
Number of orange notebooks sold = 3 u
Number of blue notebooks sold
= 5 u - 3 u
= 2 u
2 u = 20
1 u = 20 ÷ 2 = 10
Total number of notebooks sold
= 5 u
= 5 x 10
= 50
(b)
Percent of the notebooks left unsold = 100% - 50% = 50% 50% of the notebooks that were sold = 5 u 50% of the notebooks that were left unsold = 5 u Percent of the notebooks left unsold that were blue = 60%
Percent of the notebooks left unsold that were orange = 100% - 60% = 40%
Number of the notebooks left unsold that were orange
= 40% x 5 u
=
40100 x 5 u
= 2 u
Number of orange notebooks that Tom had at first
= 2 u + 3 u
= 5 u
= 5 x 10
= 50
Answer(s): (a) 50; (b) 50
