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