PSLE Ian had blue pens and red pens for sale. He sold 60 blue pens. 60% of the pens sold were red.
- How many blue pens and red pens did Ian sell altogether?
- He sold 50% of his pens. 75% of the pens left unsold were blue. How many red pens did Ian have at first?
| |
Blue |
Red |
Total |
Total in percent |
| Before |
5.75 u |
4.25 u |
10 u |
100% |
| Change |
- 40%
- 2 u |
- 60%
- 3 u |
- 100%
- 5 u |
- 50% |
| After |
75%
3.75 u |
25%
1.25 u |
100%
5 u |
50%
|
60% =
60100 =
35 Total number of pens sold = 5 u
Number of red pens sold = 3 u
Number of blue pens sold
= 5 u - 3 u
= 2 u
2 u = 60
1 u = 60 ÷ 2 = 30
Total number of pens sold
= 5 u
= 5 x 30
= 150
(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 blue = 75%
Percent of the pens left unsold that were red = 100% - 75% = 25%
Number of the pens left unsold that were red
= 25% x 5 u
=
25100 x 5 u
= 1.25 u
Number of red pens that Ian had at first
= 1.25 u + 3 u
= 4.25 u
= 4.25 x 30
= 127.5
Answer(s): (a) 150; (b) 127.5
