PSLE Eric had green pens and blue pens for sale. He sold 210 green pens. 30% of the pens sold were blue.
- How many green pens and blue pens did Eric sell altogether?
- He sold 50% of his pens. 70% of the pens left unsold were green. How many blue pens did Eric have at first?
| |
Green |
Blue |
Total |
Total in percent |
| Before |
14 u |
6 u |
20 u |
100% |
| Change |
- 70%
- 7 u |
- 30%
- 3 u |
- 100%
- 10 u |
- 50% |
| After |
70%
7 u |
30%
3 u |
100%
10 u |
50%
|
30% =
30100 =
310 Total number of pens sold = 10 u
Number of blue pens sold = 3 u
Number of green pens sold
= 10 u - 3 u
= 7 u
7 u = 210
1 u = 210 ÷ 7 = 30
Total number of pens sold
= 10 u
= 10 x 30
= 300
(b)
Percent of the pens left unsold = 100% - 50% = 50% 50% of the pens that were sold = 10 u 50% of the pens that were left unsold = 10 u Percent of the pens left unsold that were green = 70%
Percent of the pens left unsold that were blue = 100% - 70% = 30%
Number of the pens left unsold that were blue
= 30% x 10 u
=
30100 x 10 u
= 3 u
Number of blue pens that Eric had at first
= 3 u + 3 u
= 6 u
= 6 x 30
= 180
Answer(s): (a) 300; (b) 180
