GMAT Diagnostic Test Question 22

Question

GMAT Diagnostic Test Question 22 
Field: word problems (overlapping sets)
Difficulty: 650
 Rating:  yellow/79350

60% of the San Diego Zoo visitors are single without children, and the rest are married with children. If 25% of the married visitors have multiple children, what percentage of the San Diego Zoo visitors have only one child?

A. 15
B. 20
C. 30
D. 50
E. 75

dzyubam · Answer

Explanation: 
 Rating:  yellow/793502 
 Official Answer: C

There are  100% - 60% = 40%  married visitors in the zoo. If all married visitors have children, then we'll distinguish between two groups of married visitors, those with multiple children and those with only one child. Thus there are  100% - 25% = 75%  married visitors with only one child among all married visitors. We know that married visitors constitute 40% of all San Diego Zoo visitors and 75% of these married visitors have only one child. Consequently,  40% * 75% = 30%  of all San Diego Zoo visitors have only one child.

seofah · Answer

Pdf release has as "what percentage of the San Diego Zoo family visitors have only one child" Please amend

powerka · Answer

To me this seems to be a 650 problem, and not 750.

azule45 · Answer

i gotta agree, this seemed a little bit easier than a 750 might be. i'd think its a 650. MAYBE a 700. but then again, what would i know. i haven't taken the test yet and won't for about 3 more months.

bb · Answer

Thank you. This feedback helps!

jtk25 · Answer

i tend to like to plug in numbers when possible so i approached this question as saying

100 people visited the zoo.

40 families (40% of 100)
10 with multiple children (25% of 40)
Therefore 30 with single children (40-10)

30/100 = 30%.

james12345 · Answer

rated it low because this is below even a 650 question in my opinion. Still love the diagnostic test though!

wilbase · Answer

totally agree. This one is a bit easy.

ra011y · Answer

This looks like it can be a 650 question at max. More likely a 600 question. Thanks for the awesome test!

AloneAndInsufficient · Answer

This is a badly-worded question.

1) It assumes that single visitors do not have children. This is certainly not a reflection of real life, so how are we supposed to know this when we first read the question?

2) There's no such thing as a "family visitor" in the English language. If you're going to distinguish this from "single", then maybe use "married". Otherwise, it's impossible for the reader to know that to "single" and "family" are mutually disjoint sets.

Here's what I would write:

60% of the San Diego Zoo visitors are single without children, and the rest are married with children. If 25% of the married visitors have multiple children, what percentage of the San Diego Zoo visitors have only one child?

dzyubam · Answer

Thanks, I we will correct that. +1.

sings33 · Answer

I think its easier if you think of it like this.

60% are single w/o children which equals 40% are married w/ children (1-.6)
25% of the 40% have multiple children. So 25% of 40% is 10% (.25*.4 = .1 or 10%)

So just subtract married w/ children(40%) from married visitors w/o multiple children (10%) and you get married with 1 child
40% - 10% (.4-.1) = 30%

mrwuzzman · Answer

I have to agree with AloneAndInsufficient, who mentioned the poor wording of the question. I got tripped up because apparently the question is including everybody in a family as one visitor.

"60% of the San Diego Zoo visitors are single and all of the San Diego Zoo family visitors have children. If 25% of families visiting the San Diego Zoo have multiple children, what percentage of the San Diego Zoo visitors have only one child?"

75 percent of families have one child. But the question, instead of counting two parents and a child as three people, it counts them as one. I was confused by that, because I thought 10 families with a child each would count as 30 people, rather than 10 visitors.

Maybe I'm the only one tripped up by that. But it's either something to correct in the diagnostic, or a good lesson to us newbies that the GMAT can sometimes use ambiguous wording and not to dig too deeply into the question.

emilianoluzzi · Answer

It cannot be a 750 level question...

subhajeet · Answer

Easy one take x=100 and now solve.

will get the answer as 30.

BCG13 · Answer

This question is too easy to be 700+.

Lets assume that 100 is our total number of visitors to the zoo. 
so, .6*100 will give us 60, so 100-60 will give us 40 married visitors with children. 
so, if we take .25 * 40 will give us 10; therefore, we can 40-10 will give us = 30. 
___
Answer. C

GMAT Diagnostic Test Question 22

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards