Sabrina baked 50 cupcakes. 40% of them were butter cupcakes. How many more butter cupcakes must Sabrina bake so that 70% of her cupcakes are butter cupcakes?
| |
Butter cupcakes |
Other cupcakes |
| Before |
40% |
60% |
| Change |
+ ? |
No change |
| After |
70 u |
30 u |
Number of butter cupcakes at first
= 40% x 50
=
40100 x 50
= 20
Percentage of other cupcakes
= 100% - 40%
= 60%
Number of other cupcakes
= 60% x 50
=
60100 x 50
= 30
Number of other cupcakes in the end
= 100 u - 70 u
= 30 u
The number of other cupcakes remains unchanged.
60% = 30 u
30 u = 30
1 u = 30 ÷ 30 = 1
Number of butter cupcakes in the end
= 70 u
= 70 x 1
= 70
Additional number of butter cupcakes that Sabrina must bake
= 70 - 20
= 50
Answer(s): 50
