GMAT Official Guide 2019 The table shows partial results

BTGmoderatorDC wrote:

The table shows partial results of a survey in which consumers were asked to indicate which one of six promotional techniques most influenced their decision to buy a new food product. Of those consumers who indicated one of the four techniques listed, what fraction indicated either coupons or store displays?


A. 2/7

B. 1/3

C. 2/5

D. 4/9

E. 1/2

Since we aren't told the number of people involved in the survey, let's make things easier on ourselves and assign a "nice" value to the number of people involved in the survey.
Let's say there were 100 people in the survey.

When we apply this to our table, we see that 35 people chose TV ads, 22 people chose coupons, 18 people chose store displays, and 15 people chose samples.

35 + 22 + 18 + 15 = 90
So, the table shows the results for 90 consumers

What fraction indicated either coupons or store displays?
Among the 90 consumers surveyed, 22 chose coupons, and 18 chose store displays
22 + 18 = 40
Fraction = 40/90
= 4/9

Answer: D

Cheers,
Brent

BTGmoderatorDC wrote:

The table shows partial results of a survey in which consumers were asked to indicate which one of six promotional techniques most influenced their decision to buy a new food product. Of those consumers who indicated one of the four techniques listed, what fraction indicated either coupons or store displays?


A. 2/7

B. 1/3

C. 2/5

D. 4/9

E. 1/2

Notice that you are instructed to use the incomplete table; the percentages add up to only 90%. So first, you will add the percentages for “Coupons” and “Store Displays,” but then you must divide by the total of 90% to get the final answer, as shown here:

(22 + 18)/(35 + 22 + 18 + 15) = 40/90 = 4/9

Answer: D

I will admit that on the first quick read, I thought "22% + 18% = 40%. Are they really just asking us to turn 40% into a fraction? That's shockingly easy!" So then, as I always do, I re-read with my skepticism radar on high alert. I then saw "partial results" and "Of those consumers who..." This was the big clue that they weren't asking for a percent of the whole; they were asking for a percent of a sub-group (this, by the way, happens often in overlapping sets).

A good moral: if a GMAT quant problem ever feels way too simple, it probably is! As I like to say, "there's no such thing as a ONE-MOVE answer."