An adviser at a municipal corporation arranges concession on bills raised to the public and charges 50 percent of the concession made, as his fee. The adviser arranged concession on a bill raised to Mr. Stephen by the municipal corporation. What percent of the amount originally billed to Mr. Stephen did the adviser charge as his fee?

Let the amount on the bill raised to Mr. Stephen be X
Let the concession arranged be Y
Then the adviser charge is Y/2
Then the total amount paid by Mr.Stephen after the concession = X-Y

The question can now be rephrased to, What is the value of ((1/2)*Y)/X

I.The adviser charged Mr. Stephen $40, as his fee.

(1/2)*Y = $40. Since we don't know the value of X. We cannot answer the question.

II.The adviser charged Mr. Stephen 25 percent of what Mr. Stephen paid to the municipal corporation after concession, as his fee.

Adviser charge = Y/2
Total amount paid by Mr.Stephen after the concession = X-Y
Y/2 = 1/4(X-Y)
(3/4)*(Y) = (1/4)*(X)
So, ((1/2)*Y)/X = 1/6

IMO B

neelgandham wrote:An adviser at a municipal corporation arranges concession on bills raised to the public and charges 50 percent of the concession made, as his fee. The adviser arranged concession on a bill raised to Mr. Stephen by the municipal corporation. What percent of the amount originally billed to Mr. Stephen did the adviser charge as his fee?

Let the amount on the bill raised to Mr. Stephen be X
Let the concession arranged be Y
Then the adviser charge is Y/2
Then the total amount paid by Mr.Stephen after the concession = X-Y

The question can now be rephrased to, What is the value of ((1/2)*Y)/X

I.The adviser charged Mr. Stephen $40, as his fee.

(1/2)*Y = $40. Since we don't know the value of X. We cannot answer the question.

II.The adviser charged Mr. Stephen 25 percent of what Mr. Stephen paid to the municipal corporation after concession, as his fee.

Adviser charge = Y/2
Total amount paid by Mr.Stephen after the concession = X-Y
Y/2 = 1/4(X-Y)
(3/4)*(Y) = (1/4)*(X)
So, ((1/2)*Y)/X = 1/6

IMO B

If we can foresee a relation in two variables, we can determine any ratio or percent pertaining to the two variables. This is important on DS, the moment we realize whether there's a way or not to answer the target question uniquely, we can afford to take the decision without finishing the calculation. It saves our time and effort.

Fee = concession/2

To find: Fee/Original_Amount * 100

Statement 1:
There is no direct relation between concession & Original Amount
INSUFFICIENT

Statement 2:
Fee = (Original - Concession)/4
4*Fee = (Original - 2*Fee)
6*Fee = Original
SUFFICIENT

[spoiler]{B}[/spoiler]