Irene baked 40 cookies. 25% of them were cream cookies. How many more cream cookies must Irene bake so that 85% of her cookies are cream cookies?
| |
Cream cookies |
Other cookies |
| Before |
25% |
75% |
| Change |
+ ? |
No change |
| After |
85 u |
15 u |
Number of cream cookies at first
= 25% x 40
=
25100 x 40
= 10
Percentage of other cookies
= 100% - 25%
= 75%
Number of other cookies
= 75% x 40
=
75100 x 40
= 30
Number of other cookies in the end
= 100 u - 85 u
= 15 u
The number of other cookies remains unchanged.
75% = 15 u
15 u = 30
1 u = 30 ÷ 15 = 2
Number of cream cookies in the end
= 85 u
= 85 x 2
= 170
Additional number of cream cookies that Irene must bake
= 170 - 10
= 160
Answer(s): 160
