PSLE Reggie had black pens and yellow pens for sale. He sold 40 black pens. 60% of the pens sold were yellow.
- How many black pens and yellow pens did Reggie sell altogether?
- He sold 50% of his pens. 60% of the pens left unsold were black. How many yellow pens did Reggie have at first?
| |
Black |
Yellow |
Total |
Total in percent |
| Before |
5 u |
5 u |
10 u |
100% |
| Change |
- 40%
- 2 u |
- 60%
- 3 u |
- 100%
- 5 u |
- 50% |
| After |
60%
3 u |
40%
2 u |
100%
5 u |
50%
|
60% =
60100 =
35 Total number of pens sold = 5 u
Number of yellow pens sold = 3 u
Number of black pens sold
= 5 u - 3 u
= 2 u
2 u = 40
1 u = 40 ÷ 2 = 20
Total number of pens sold
= 5 u
= 5 x 20
= 100
(b)
Percent of the pens left unsold = 100% - 50% = 50% 50% of the pens that were sold = 5 u 50% of the pens that were left unsold = 5 u Percent of the pens left unsold that were black = 60%
Percent of the pens left unsold that were yellow = 100% - 60% = 40%
Number of the pens left unsold that were yellow
= 40% x 5 u
=
40100 x 5 u
= 2 u
Number of yellow pens that Reggie had at first
= 2 u + 3 u
= 5 u
= 5 x 20
= 100
Answer(s): (a) 100; (b) 100
