Penelope baked 140 tarts. 25% of them were butter tarts. How many more butter tarts must Penelope bake so that 85% of her tarts are butter tarts?
| |
Butter tarts |
Other tarts |
| Before |
25% |
75% |
| Change |
+ ? |
No change |
| After |
85 u |
15 u |
Number of butter tarts at first
= 25% x 140
=
25100 x 140
= 35
Percentage of other tarts
= 100% - 25%
= 75%
Number of other tarts
= 75% x 140
=
75100 x 140
= 105
Number of other tarts in the end
= 100 u - 85 u
= 15 u
The number of other tarts remains unchanged.
75% = 15 u
15 u = 105
1 u = 105 ÷ 15 = 7
Number of butter tarts in the end
= 85 u
= 85 x 7
= 595
Additional number of butter tarts that Penelope must bake
= 595 - 35
= 560
Answer(s): 560
