Marion baked 120 wafers. 25% of them were matcha wafers. How many more matcha wafers must Marion bake so that 90% of her wafers are matcha wafers?
| |
Matcha wafers |
Other wafers |
| Before |
25% |
75% |
| Change |
+ ? |
No change |
| After |
90 u |
10 u |
Number of matcha wafers at first
= 25% x 120
=
25100 x 120
= 30
Percentage of other wafers
= 100% - 25%
= 75%
Number of other wafers
= 75% x 120
=
75100 x 120
= 90
Number of other wafers in the end
= 100 u - 90 u
= 10 u
The number of other wafers remains unchanged.
75% = 10 u
10 u = 90
1 u = 90 ÷ 10 = 9
Number of matcha wafers in the end
= 90 u
= 90 x 9
= 810
Additional number of matcha wafers that Marion must bake
= 810 - 30
= 780
Answer(s): 780
