PSLE Billy had blue staplers and yellow staplers for sale. He sold 90 blue staplers. 40% of the staplers sold were yellow.
- How many blue staplers and yellow staplers did Billy sell altogether?
- He sold 50% of his staplers. 80% of the staplers left unsold were blue. How many yellow staplers did Billy have at first?
| |
Blue |
Yellow |
Total |
Total in percent |
| Before |
7 u |
3 u |
10 u |
100% |
| Change |
- 60%
- 3 u |
- 40%
- 2 u |
- 100%
- 5 u |
- 50% |
| After |
80%
4 u |
20%
1 u |
100%
5 u |
50%
|
40% =
40100 =
25 Total number of staplers sold = 5 u
Number of yellow staplers sold = 2 u
Number of blue 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 blue = 80%
Percent of the staplers left unsold that were yellow = 100% - 80% = 20%
Number of the staplers left unsold that were yellow
= 20% x 5 u
=
20100 x 5 u
= 1 u
Number of yellow staplers that Billy had at first
= 1 u + 2 u
= 3 u
= 3 x 30
= 90
Answer(s): (a) 150; (b) 90
