PSLE Tim had gold pencils and red pencils for sale. He sold 30 gold pencils. 40% 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 |
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 pencils sold = 5 u
Number of red pencils sold = 2 u
Number of gold pencils sold
= 5 u - 2 u
= 3 u
3 u = 30
1 u = 30 ÷ 3 = 10
Total number of pencils sold
= 5 u
= 5 x 10
= 50
(b)
Percent of the pencils left unsold = 100% - 50% = 50% 50% of the pencils that were sold = 5 u 50% of the pencils that were left unsold = 5 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 5 u
=
25100 x 5 u
= 1.25 u
Number of red pencils that Tim had at first
= 1.25 u + 2 u
= 3.25 u
= 3.25 x 10
= 32.5
Answer(s): (a) 50; (b) 32.5