Diana baked 100 cookies. 40% of them were blueberry cookies. How many more blueberry cookies must Diana bake so that 90% of her cookies are blueberry cookies?
| |
Blueberry cookies |
Other cookies |
| Before |
40% |
60% |
| Change |
+ ? |
No change |
| After |
90 u |
10 u |
Number of blueberry cookies at first
= 40% x 100
=
40100 x 100
= 40
Percentage of other cookies
= 100% - 40%
= 60%
Number of other cookies
= 60% x 100
=
60100 x 100
= 60
Number of other cookies in the end
= 100 u - 90 u
= 10 u
The number of other cookies remains unchanged.
60% = 10 u
10 u = 60
1 u = 60 ÷ 10 = 6
Number of blueberry cookies in the end
= 90 u
= 90 x 6
= 540
Additional number of blueberry cookies that Diana must bake
= 540 - 40
= 500
Answer(s): 500
