Zara baked 80 biscuits. 25% of them were chocolate biscuits. How many more chocolate biscuits must Zara bake so that 85% of her biscuits are chocolate biscuits?
| |
Chocolate biscuits |
Other biscuits |
| Before |
25% |
75% |
| Change |
+ ? |
No change |
| After |
85 u |
15 u |
Number of chocolate biscuits at first
= 25% x 80
=
25100 x 80
= 20
Percentage of other biscuits
= 100% - 25%
= 75%
Number of other biscuits
= 75% x 80
=
75100 x 80
= 60
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 = 60
1 u = 60 ÷ 15 = 4
Number of chocolate biscuits in the end
= 85 u
= 85 x 4
= 340
Additional number of chocolate biscuits that Zara must bake
= 340 - 20
= 320
Answer(s): 320
