Jp27 wrote:

A store sells a certain product at a fixed price per unit. At the product's current price, q units cost a total of exactly $300. If the price were lowered by $5 from its current value, then q + 2n units would cost exactly $300; if the price were raised by $5, then q – n units would cost exactly $300. What is the value of q?

A. 10

B. 15

C. 20

D. 25

E. 30

Is there any easy way to solve this problem? Ans is the real exam going to have these sort of problems?

Cheers

A very simple solution to this question can be framed which will take approx 2 minutes by following method.

1st case : price is lowered by $5

So Total price lowered = 5q

This lead to increase in number of units by 2n

So, 5q = 2n(300/q - 5)

5q/2n = 300/q - 5 ...........................(i)

2nd case : price is increased by $5

So, total price increased = 5q

This lead to decrease in number of units by n.

So, 5q = n(300/q +5)

5q/n = 300/q + 5.............................(ii)

From (i) * 2 - (ii), we get

0 = 600/q - 10 - 300/q - 5

15 = 300/q

q = 20

Answer CHope that helps. Don't forget to appreciate

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