PSLE Henry had silver notebooks and gold notebooks for sale. He sold 40 silver notebooks. 60% of the notebooks sold were gold.
- How many silver notebooks and gold notebooks did Henry sell altogether?
- He sold 50% of his notebooks. 80% of the notebooks left unsold were silver. How many gold notebooks did Henry have at first?
|
Silver |
Gold |
Total |
Total in percent |
Before |
6 u |
4 u |
10 u |
100% |
Change |
- 40% - 2 u |
- 60% - 3 u |
- 100% - 5 u |
- 50% |
After |
80% 4 u |
20% 1 u |
100% 5 u |
50%
|
60% =
60100 =
35 Total number of notebooks sold = 5 u
Number of gold notebooks sold = 3 u
Number of silver notebooks sold
= 5 u - 3 u
= 2 u
2 u = 40
1 u = 40 ÷ 2 = 20
Total number of notebooks sold
= 5 u
= 5 x 20
= 100
(b)
Percent of the notebooks left unsold = 100% - 50% = 50% 50% of the notebooks that were sold = 5 u 50% of the notebooks that were left unsold = 5 u Percent of the notebooks left unsold that were silver = 80%
Percent of the notebooks left unsold that were gold = 100% - 80% = 20%
Number of the notebooks left unsold that were gold
= 20% x 5 u
=
20100 x 5 u
= 1 u
Number of gold notebooks that Henry had at first
= 1 u + 3 u
= 4 u
= 4 x 20
= 80
Answer(s): (a) 100; (b) 80