PSLE Tom had purple markers and black markers for sale. He sold 490 purple markers. 30% of the markers sold were black.
- How many purple markers and black markers did Tom sell altogether?
- He sold 50% of his markers. 75% of the markers left unsold were purple. How many black markers did Tom have at first?
| |
Purple |
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 markers sold = 10 u
Number of black markers sold = 3 u
Number of purple markers sold
= 10 u - 3 u
= 7 u
7 u = 490
1 u = 490 ÷ 7 = 70
Total number of markers sold
= 10 u
= 10 x 70
= 700
(b)
Percent of the markers left unsold = 100% - 50% = 50% 50% of the markers that were sold = 10 u 50% of the markers that were left unsold = 10 u Percent of the markers left unsold that were purple = 75%
Percent of the markers left unsold that were black = 100% - 75% = 25%
Number of the markers left unsold that were black
= 25% x 10 u
=
25100 x 10 u
= 2.5 u
Number of black markers that Tom had at first
= 2.5 u + 3 u
= 5.5 u
= 5.5 x 70
= 385
Answer(s): (a) 700; (b) 385
