PSLE Oscar had orange files and black files for sale. He sold 280 orange files. 30% of the files sold were black.
- How many orange files and black files did Oscar sell altogether?
- He sold 50% of his files. 75% of the files left unsold were orange. How many black files did Oscar have at first?
| |
Orange |
Black |
Total |
Total in percent |
| Before |
14.5 u |
5.5 u |
20 u |
100% |
| Change |
- 70%
- 7 u |
- 30%
- 3 u |
- 100%
- 10 u |
- 50% |
| After |
75%
7.5 u |
25%
2.5 u |
100%
10 u |
50%
|
30% =
30100 =
310 Total number of files sold = 10 u
Number of black files sold = 3 u
Number of orange files sold
= 10 u - 3 u
= 7 u
7 u = 280
1 u = 280 ÷ 7 = 40
Total number of files sold
= 10 u
= 10 x 40
= 400
(b)
Percent of the files left unsold = 100% - 50% = 50% 50% of the files that were sold = 10 u 50% of the files that were left unsold = 10 u Percent of the files left unsold that were orange = 75%
Percent of the files left unsold that were black = 100% - 75% = 25%
Number of the files left unsold that were black
= 25% x 10 u
=
25100 x 10 u
= 2.5 u
Number of black files that Oscar had at first
= 2.5 u + 3 u
= 5.5 u
= 5.5 x 40
= 220
Answer(s): (a) 400; (b) 220
