PSLE Fred had blue files and red files for sale. He sold 30 blue files. 40% of the files sold were red.
- How many blue files and red files did Fred sell altogether?
- He sold 50% of his files. 75% of the files left unsold were blue. How many red files did Fred have at first?
| |
Blue |
Red |
Total |
Total in percent |
| Before |
6.75 u |
3.25 u |
10 u |
100% |
| Change |
- 60%
- 3 u |
- 40%
- 2 u |
- 100%
- 5 u |
- 50% |
| After |
75%
3.75 u |
25%
1.25 u |
100%
5 u |
50%
|
40% =
40100 =
25 Total number of files sold = 5 u
Number of red files sold = 2 u
Number of blue files sold
= 5 u - 2 u
= 3 u
3 u = 30
1 u = 30 ÷ 3 = 10
Total number of files sold
= 5 u
= 5 x 10
= 50
(b)
Percent of the files left unsold = 100% - 50% = 50% 50% of the files that were sold = 5 u 50% of the files that were left unsold = 5 u Percent of the files left unsold that were blue = 75%
Percent of the files left unsold that were red = 100% - 75% = 25%
Number of the files left unsold that were red
= 25% x 5 u
=
25100 x 5 u
= 1.25 u
Number of red files that Fred had at first
= 1.25 u + 2 u
= 3.25 u
= 3.25 x 10
= 32.5
Answer(s): (a) 50; (b) 32.5
