At a university orientation, attendance was recorded for two optional

Question

At a university orientation, attendance was recorded for two optional activities: a campus tour and a study-skills workshop. Among 180 students, how many attended the campus tour but not the study-skills workshop?

(1) 126 students attended neither activity.

(2) 18 students attended the study-skills workshop.

M47-207

Bunuel · Accepted Answer

GMAT Club Official Solution:

At a university orientation, attendance was recorded for two optional activities: a campus tour and a study-skills workshop. Among 180 students, how many attended the campus tour but not the study-skills workshop?

We need {Tour only}.

(1) 126 students attended neither activity.

So:

{Tour or Workshop} = 180 - 126 = 54

But we do not know how many of these 54 attended the workshop, so we cannot determine {Tour only}.

Not sufficient.

(2) 18 students attended the study-skills workshop.

This gives the total number of workshop attendees, but it gives no information about how many students attended neither activity or how many attended the campus tour.

Not sufficient.

(1)+(2) From statement (1):

{Tour or Workshop} = 54

From statement (2):

{Workshop} = 18

Since everyone in {Tour or Workshop} either attended the workshop or attended the tour but not the workshop:

{Tour only} = {Tour or Workshop} - {Workshop}

{Tour only} = 54 - 18 = 36

Sufficient.

Answer: C.

vasu1104 · Answer

CT 
 CT' 
 total 
 
  SS

SS' 
 x

total

180

need to find X

S-1
SS' and CT' = 126.
but still not enough to get the value of x.

S-2
we get total value of SS. not enough to get to X.

S- 1&2

x+126 = 18
x= 136

option C

SS990 · Answer

Given : c+s+b+n=180

to find: c

1) n=126..not sufficient to find b

2) s+b =18, not suffiient to find c

together we know s+b+n, so we can find c hence c is the answer

Kakashi_7 · Answer

I have a doubt, in a situation we had

( Let College tour - a , Workshop - b, C&W - c)

The question never addresses that a student can not attend both, then why did we assume that the 18 student who attended Workshop have only attended Workshop and not both.

Am I assuming things of another possible scenario and that led me believe that union scenario can also be possible ?

Bunuel · Answer

We are  not  assuming that. The 18 students are everyone who attended the workshop, including any students who may also have attended the tour.

Among the 54 students who attended at least one activity, everyone is either in the workshop group or in Tour only. Therefore:

Tour only = 54 - 18 = 36.

So the overlap is already included within the 18 workshop attendees and does not need to be treated separately.

At a university orientation, attendance was recorded for two optional

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GMAT Data Sufficiency (DS) Questions

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