PSLE Tim had gold pencils and red pencils for sale. He sold 840 gold pencils. 30% of the pencils sold were red.
- How many gold pencils and red pencils did Tim sell altogether?
- He sold 50% of his pencils. 75% of the pencils left unsold were gold. How many red pencils did Tim have at first?
| |
Gold |
Red |
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 pencils sold = 10 u
Number of red pencils sold = 3 u
Number of gold pencils sold
= 10 u - 3 u
= 7 u
7 u = 840
1 u = 840 ÷ 7 = 120
Total number of pencils sold
= 10 u
= 10 x 120
= 1200
(b)
Percent of the pencils left unsold = 100% - 50% = 50% 50% of the pencils that were sold = 10 u 50% of the pencils that were left unsold = 10 u Percent of the pencils left unsold that were gold = 75%
Percent of the pencils left unsold that were red = 100% - 75% = 25%
Number of the pencils left unsold that were red
= 25% x 10 u
=
25100 x 10 u
= 2.5 u
Number of red pencils that Tim had at first
= 2.5 u + 3 u
= 5.5 u
= 5.5 x 120
= 660
Answer(s): (a) 1200; (b) 660
