Hi Gmat_mission,

We're told that the original price of a camera was displayed as a whole dollar amount and after adding sales tax of 10 percent, the final price was ALSO a whole dollar amount. We're asked which of the following COULD be the final price of the camera. This question is based on a Number Property rule and can be solved with a bit of 'brute force.'

To start, the only way to increase an integer by 10% and END with an integer is if the starting integer is a multiple of 10:
0 + (10% of 0) = 0
10 + (10% of 10) = 11
20 + (10% of 20) = 22
30 + (10% of 30) = 33
Etc.

If you perform that calculation with a number that is NOT a multiple of 10, then you WON'T end up with an integer:
5 + (10% of 5) = 5.5

Thus, the original price of the camera MUST be some multiple of $10. Since the Answer Choices are relatively 'close' together - and a little greater than $200 - the original price of the camera must be a little LESS than $200 (since $200 + 10% of $200 = $220, which is a little bigger than all 5 answer choices). Let's TEST the closest multiple of 10 that's LESS than 200....

IF... original price = $190, then...
the tax = 10% of $190 = $19...
and the total price = $190 + $19 = $209

Final Answer: B

GMAT assassins aren't born, they're made,
Rich