If a store sold 30 more televisions this month than last

[BTGmoderatorLU]

Source: Princeton Review

If a store sold 30 more televisions this month than last month, by what percent has the number of televisions sold increased from last month to this month?

1) This month the store sold 150 televisions.
2) Last month the store sold 80% as many televisions as this month.

The OA is D.

[Jay@ManhattanReview]

Source: Princeton Review

If a store sold 30 more televisions this month than last month, by what percent has the number of televisions sold increased from last month to this month?

1) This month the store sold 150 televisions.
2) Last month the store sold 80% as many televisions as this month.

The OA is D.

Percentage increase in the number of TVs sold this month over the last month is given by

[(# of TVs sold this month - # of TVs sold last month) / (# of TVs sold last month)]*100%

= [30 / (# of TVs sold last month)]*100%

So, if we know the value of "# of TVs sold last month", we get the answer.

Question rephrased: How many TVs sold last month?

Let's take each statement one by one.

1) This month the store sold 150 televisions.

=> # of TVs sold last month = 150 - 30 = 120. Sufficient.

2) Last month the store sold 80% as many televisions as this month.

Say # of TVs sold this month = x; thus # of TVs sold last month = 80% of x = 0.8x

Thus, # of TVs sold this month - # of TVs sold last month = x - 0.8x = 0.2x = 30 (given)

=> x = 30/0.2 = 150.

=> # of TVs sold last month = 0.8x = 0.8*150 = 120. Sufficient.

The correct answer: D

Hope this helps!

-Jay
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