If the price of a chocolate bar is doubled, by what percent will sales

Direct inverse proportional relationship doesn't imply that 1 cent increase in price leads to 1% decrease in sales.

Even if we assume that it implies that then the first statement contradicts it.

So I will stick with choice C.

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Hi Bunuel,

Please provide your explanation of arriving at the correct answer.

Thanks,
Pallavi

Bunuel wrote:
If the price of a chocolate bar is doubled, by what percent will sales (quantity sold) of the chocolate bar decrease? Assume a direct inverse proportional relationship between price increase in cents versus sales decrease by percentage.

(1) For every 15 cent increase in price, the sales (quantity sold) will decrease by 10%

(2) Each chocolate bar now costs 99 cents
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Let 'P' be the price increase in cents, 'a' be the initial price of the chocolate in cents and 'n' be the corresponding percentage decrease.

A/Q: P = k/n where k is a constant

(A) 15 = k/10 => k = 150

As the price is doubled, the price basically increases by 'a' cents. Therefore:-

a = k/n = 150/n or n = 150/a

As a is not known, Not Sufficient

(B) 2a = 99 => a = 49.5. Not Sufficient alone

(A) + (B) -> Sufficient. Option C

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