Bunuel wrote:

If the price of a chocolate bar is doubled, by what percent will sales (quantity sold) of the chocolate bar decrease?

(1) For every 15 cent increase in price, the sales (quantity sold) will decrease by 10%. We don't know the price of the bar. Not sufficient.

(2) Each chocolate bar now costs 99 cents. We don't know how increase in price affects the quantity sold. Not sufficient.

(1)+(2) If we double the price it'll increase by 99 cents, so the sales must decrease by 99/15*10=66%. Sufficient.

Answer: C.

Does this make sense?

sorry !

Although got the answer as C still can't understand how we get 66%.

after doubling the price becomes 99 cents so initially the price was 49.5 cents

now it says for every 15 cent increase the price decreased by 10 %

so a total increase of 49.5 cents took place, how many 15 cents increases are there?

so 49.5/15 = 3.3

meaning after 1st 15 cent increase price becomes 49.5 +15 = 64.5 and sales decreases by 10 %

after second 15 cent increase price becomes 79.5 and sales decreases by another 10 %

after third 15 cent increase price becomes 94.5 and sales decreases by another 10%

for the remaining 4.5 cents increase sales will decrease by less than 10 %

So I was expecting that sales would decrease by something between 30% - 35% .

What am I doing wrong ?

Thank you

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- Stne