It is currently 18 Feb 2019, 02:01

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Set S and Set T both contain x elements. The average of Set

Author Message
TAGS:
Senior Manager
Joined: 20 May 2014
Posts: 282
Followers: 18

Kudos [?]: 50 [0], given: 220

Set S and Set T both contain x elements. The average of Set [#permalink]  16 Oct 2017, 08:30
00:00

Question Stats:

50% (00:41) correct 50% (00:55) wrong based on 2 sessions
Set S and Set T both contain x elements. The average of Set S is 40. If the average of Set S and Set T combined is 50, which of the following must be true?

I. The average of Set T is 60.

II. The range of Set T is greater than that of Set S.

III. x is an even number

(A) I only

(B) I & II

(C) II only

(D) I & III

(E) All of the above

Kudos for correct solution.
[Reveal] Spoiler: OA
Director
Joined: 03 Sep 2017
Posts: 521
Followers: 1

Kudos [?]: 343 [1] , given: 66

Re: Set S and Set T both contain x elements. The average of Set [#permalink]  16 Oct 2017, 09:42
1
KUDOS
We can rewrite the information we have in formulas, i.e. given the mean of set S being 40, the combined mean is computed as $$\frac{40x+?x}{2x}=50$$, where ? is the mean of set T.
Doing computations, we get $$40x+?x = 100x$$, thus $$?=60$$. The mean of set T is 60 ans I is true.

Then, moving to the other statements, knowing the mean of the sets does not give any information about the members of the set so that we cannot infer anything about the range, so II is false. Finally, there is no reason why x should be even to get the results we have because the mean does not depend on the elements being an odd or even number, thus II is false too.

Re: Set S and Set T both contain x elements. The average of Set   [#permalink] 16 Oct 2017, 09:42
Display posts from previous: Sort by