PSLE Fred had purple pencils and yellow pencils for sale. He sold 160 purple pencils. 60% of the pencils sold were yellow.
- How many purple pencils and yellow pencils did Fred sell altogether?
- He sold 50% of his pencils. 80% of the pencils left unsold were purple. How many yellow pencils did Fred have at first?
| |
Purple |
Yellow |
Total |
Total in percent |
| Before |
6 u |
4 u |
10 u |
100% |
| Change |
- 40%
- 2 u |
- 60%
- 3 u |
- 100%
- 5 u |
- 50% |
| After |
80%
4 u |
20%
1 u |
100%
5 u |
50%
|
60% =
60100 =
35 Total number of pencils sold = 5 u
Number of yellow pencils sold = 3 u
Number of purple pencils sold
= 5 u - 3 u
= 2 u
2 u = 160
1 u = 160 ÷ 2 = 80
Total number of pencils sold
= 5 u
= 5 x 80
= 400
(b)
Percent of the pencils left unsold = 100% - 50% = 50% 50% of the pencils that were sold = 5 u 50% of the pencils that were left unsold = 5 u Percent of the pencils left unsold that were purple = 80%
Percent of the pencils left unsold that were yellow = 100% - 80% = 20%
Number of the pencils left unsold that were yellow
= 20% x 5 u
=
20100 x 5 u
= 1 u
Number of yellow pencils that Fred had at first
= 1 u + 3 u
= 4 u
= 4 x 80
= 320
Answer(s): (a) 400; (b) 320
