PSLE Glen had black pencils and purple pencils for sale. He sold 180 black pencils. 40% of the pencils sold were purple.
- How many black pencils and purple pencils did Glen sell altogether?
- He sold 50% of his pencils. 80% of the pencils left unsold were black. How many purple pencils did Glen have at first?
| |
Black |
Purple |
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 pencils sold = 5 u
Number of purple pencils sold = 2 u
Number of black pencils sold
= 5 u - 2 u
= 3 u
3 u = 180
1 u = 180 ÷ 3 = 60
Total number of pencils sold
= 5 u
= 5 x 60
= 300
(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 black = 80%
Percent of the pencils left unsold that were purple = 100% - 80% = 20%
Number of the pencils left unsold that were purple
= 20% x 5 u
=
20100 x 5 u
= 1 u
Number of purple pencils that Glen had at first
= 1 u + 2 u
= 3 u
= 3 x 60
= 180
Answer(s): (a) 300; (b) 180
