PSLE Ken had gold notebooks and pink notebooks for sale. He sold 350 gold notebooks. 30% of the notebooks sold were pink.
- How many gold notebooks and pink notebooks did Ken sell altogether?
- He sold 50% of his notebooks. 80% of the notebooks left unsold were gold. How many pink notebooks did Ken have at first?
|
Gold |
Pink |
Total |
Total in percent |
Before |
15 u |
5 u |
20 u |
100% |
Change |
- 70% - 7 u |
- 30% - 3 u |
- 100% - 10 u |
- 50% |
After |
80% 8 u |
20% 2 u |
100% 10 u |
50%
|
30% =
30100 =
310 Total number of notebooks sold = 10 u
Number of pink notebooks sold = 3 u
Number of gold notebooks sold
= 10 u - 3 u
= 7 u
7 u = 350
1 u = 350 ÷ 7 = 50
Total number of notebooks sold
= 10 u
= 10 x 50
= 500
(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 gold = 80%
Percent of the notebooks left unsold that were pink = 100% - 80% = 20%
Number of the notebooks left unsold that were pink
= 20% x 10 u
=
20100 x 10 u
= 2 u
Number of pink notebooks that Ken had at first
= 2 u + 3 u
= 5 u
= 5 x 50
= 250
Answer(s): (a) 500; (b) 250