Barbara baked 80 muffins. 25% of them were cream muffins. How many more cream muffins must Barbara bake so that 70% of her muffins are cream muffins?
| |
Cream muffins |
Other muffins |
| Before |
25% |
75% |
| Change |
+ ? |
No change |
| After |
70 u |
30 u |
Number of cream muffins at first
= 25% x 80
=
25100 x 80
= 20
Percentage of other muffins
= 100% - 25%
= 75%
Number of other muffins
= 75% x 80
=
75100 x 80
= 60
Number of other muffins in the end
= 100 u - 70 u
= 30 u
The number of other muffins remains unchanged.
75% = 30 u
30 u = 60
1 u = 60 ÷ 30 = 2
Number of cream muffins in the end
= 70 u
= 70 x 2
= 140
Additional number of cream muffins that Barbara must bake
= 140 - 20
= 120
Answer(s): 120
