Rachel baked 100 biscuits. 25% of them were cream biscuits. How many more cream biscuits must Rachel bake so that 85% of her biscuits are cream biscuits?
| |
Cream biscuits |
Other biscuits |
| Before |
25% |
75% |
| Change |
+ ? |
No change |
| After |
85 u |
15 u |
Number of cream biscuits at first
= 25% x 100
=
25100 x 100
= 25
Percentage of other biscuits
= 100% - 25%
= 75%
Number of other biscuits
= 75% x 100
=
75100 x 100
= 75
Number of other biscuits in the end
= 100 u - 85 u
= 15 u
The number of other biscuits remains unchanged.
75% = 15 u
15 u = 75
1 u = 75 ÷ 15 = 5
Number of cream biscuits in the end
= 85 u
= 85 x 5
= 425
Additional number of cream biscuits that Rachel must bake
= 425 - 25
= 400
Answer(s): 400
