Xandra baked 150 wafers. 40% of them were vanila wafers. How many more vanila wafers must Xandra bake so that 90% of her wafers are vanila wafers?
| |
Vanila wafers |
Other wafers |
| Before |
40% |
60% |
| Change |
+ ? |
No change |
| After |
90 u |
10 u |
Number of vanila wafers at first
= 40% x 150
=
40100 x 150
= 60
Percentage of other wafers
= 100% - 40%
= 60%
Number of other wafers
= 60% x 150
=
60100 x 150
= 90
Number of other wafers in the end
= 100 u - 90 u
= 10 u
The number of other wafers remains unchanged.
60% = 10 u
10 u = 90
1 u = 90 ÷ 10 = 9
Number of vanila wafers in the end
= 90 u
= 90 x 9
= 810
Additional number of vanila wafers that Xandra must bake
= 810 - 60
= 750
Answer(s): 750
