PSLE Howard had red notebooks and pink notebooks for sale. He sold 840 red notebooks. 30% of the notebooks sold were pink.
- How many red notebooks and pink notebooks did Howard sell altogether?
- He sold 50% of his notebooks. 70% of the notebooks left unsold were red. How many pink notebooks did Howard have at first?
|
Red |
Pink |
Total |
Total in percent |
Before |
14 u |
6 u |
20 u |
100% |
Change |
- 70% - 7 u |
- 30% - 3 u |
- 100% - 10 u |
- 50% |
After |
70% 7 u |
30% 3 u |
100% 10 u |
50%
|
30% =
30100 =
310 Total number of notebooks sold = 10 u
Number of pink notebooks sold = 3 u
Number of red notebooks sold
= 10 u - 3 u
= 7 u
7 u = 840
1 u = 840 ÷ 7 = 120
Total number of notebooks sold
= 10 u
= 10 x 120
= 1200
(b)
Percent of the notebooks left unsold = 100% - 50% = 50% 50% of the notebooks that were sold = 10 u 50% of the notebooks that were left unsold = 10 u Percent of the notebooks left unsold that were red = 70%
Percent of the notebooks left unsold that were pink = 100% - 70% = 30%
Number of the notebooks left unsold that were pink
= 30% x 10 u
=
30100 x 10 u
= 3 u
Number of pink notebooks that Howard had at first
= 3 u + 3 u
= 6 u
= 6 x 120
= 720
Answer(s): (a) 1200; (b) 720