PSLE Neave had silver files and blue files for sale. He sold 30 silver files. 70% of the files sold were blue.
- How many silver files and blue files did Neave sell altogether?
- He sold 50% of his files. 80% of the files left unsold were silver. How many blue files did Neave have at first?
| |
Silver |
Blue |
Total |
Total in percent |
| Before |
11 u |
9 u |
20 u |
100% |
| Change |
- 30%
- 3 u |
- 70%
- 7 u |
- 100%
- 10 u |
- 50% |
| After |
80%
8 u |
20%
2 u |
100%
10 u |
50%
|
70% =
70100 =
710 Total number of files sold = 10 u
Number of blue files sold = 7 u
Number of silver files sold
= 10 u - 7 u
= 3 u
3 u = 30
1 u = 30 ÷ 3 = 10
Total number of files sold
= 10 u
= 10 x 10
= 100
(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 silver = 80%
Percent of the files left unsold that were blue = 100% - 80% = 20%
Number of the files left unsold that were blue
= 20% x 10 u
=
20100 x 10 u
= 2 u
Number of blue files that Neave had at first
= 2 u + 7 u
= 9 u
= 9 x 10
= 90
Answer(s): (a) 100; (b) 90
