PSLE Carl had green staplers and black staplers for sale. He sold 90 green staplers. 40% of the staplers sold were black.
- How many green staplers and black staplers did Carl sell altogether?
- He sold 50% of his staplers. 60% of the staplers left unsold were green. How many black staplers did Carl have at first?
| |
Green |
Black |
Total |
Total in percent |
| Before |
6 u |
4 u |
10 u |
100% |
| Change |
- 60%
- 3 u |
- 40%
- 2 u |
- 100%
- 5 u |
- 50% |
| After |
60%
3 u |
40%
2 u |
100%
5 u |
50%
|
40% =
40100 =
25 Total number of staplers sold = 5 u
Number of black staplers sold = 2 u
Number of green staplers sold
= 5 u - 2 u
= 3 u
3 u = 90
1 u = 90 ÷ 3 = 30
Total number of staplers sold
= 5 u
= 5 x 30
= 150
(b)
Percent of the staplers left unsold = 100% - 50% = 50% 50% of the staplers that were sold = 5 u 50% of the staplers that were left unsold = 5 u Percent of the staplers left unsold that were green = 60%
Percent of the staplers left unsold that were black = 100% - 60% = 40%
Number of the staplers left unsold that were black
= 40% x 5 u
=
40100 x 5 u
= 2 u
Number of black staplers that Carl had at first
= 2 u + 2 u
= 4 u
= 4 x 30
= 120
Answer(s): (a) 150; (b) 120
