Question:
A circular logo is enlarged to fit the lid of a jar. The new diameter is 50 per cent larger than the original. By what percentage has the area of the logo increased?

Option A):
50
Option B):
100
Option C):
125
Option D):
80

Correct Answer is Option C):
125

Explanation:
If the diameter of the old lid is 100, the diameter of the new lid will be 150.
This gives a ratio of 2 : 3
The areas of the lids will be in the ratio (2)2 : (3)2 . or 4 : 9
This represents an increase in area of 5units for every 4 units
5/4 is equivalent to 125 percent.