PSLE David had pink pencils and purple pencils for sale. He sold 180 pink pencils. 70% of the pencils sold were purple.
- How many pink pencils and purple pencils did David sell altogether?
- He sold 50% of his pencils. 70% of the pencils left unsold were pink. How many purple pencils did David have at first?
| |
Pink |
Purple |
Total |
Total in percent |
| Before |
10 u |
10 u |
20 u |
100% |
| Change |
- 30%
- 3 u |
- 70%
- 7 u |
- 100%
- 10 u |
- 50% |
| After |
70%
7 u |
30%
3 u |
100%
10 u |
50%
|
70% =
70100 =
710 Total number of pencils sold = 10 u
Number of purple pencils sold = 7 u
Number of pink pencils sold
= 10 u - 7 u
= 3 u
3 u = 180
1 u = 180 ÷ 3 = 60
Total number of pencils sold
= 10 u
= 10 x 60
= 600
(b)
Percent of the pencils left unsold = 100% - 50% = 50% 50% of the pencils that were sold = 10 u 50% of the pencils that were left unsold = 10 u Percent of the pencils left unsold that were pink = 70%
Percent of the pencils left unsold that were purple = 100% - 70% = 30%
Number of the pencils left unsold that were purple
= 30% x 10 u
=
30100 x 10 u
= 3 u
Number of purple pencils that David had at first
= 3 u + 7 u
= 10 u
= 10 x 60
= 600
Answer(s): (a) 600; (b) 600
