Question

I need help on this question. Please ?

Answer 1

Let original diameter be x
area =
`\pi (x/2)^(2)`

After the original diameter has increased by 50%
x = 1.5x
area =
`\pi (3x/4)^(2)`

changes in area =
`\pi (3x/4)^(2)` -
`\pi (x/2)^(2)`
changes in area =
`\pi [(3x/4)^(2) -(x/2)^(2)]`
changes in area =
`\pi [9x^2/16 - x^2/4]`
changes in area =
`\pi [9x^2/16 - 4x^2/16]`
changes in area =
`\pi [5x^2/16]`

Change in area =
`\pi [5x^2/16]` /
`\pi (x/2)^(2)` x 100
Change in area =
`[5x^2/16]` x
`[4/x^2]` x 100
Change in area = 5/4 x 100
Change in area = 125% (Answer D)

Answer 2

The answer would be: A. 50