Ages of Ann, Bea and Cho

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Couldn't you put 9 and 1 as

kingerikclusters - September 28, 2017

Couldn't you put 9 and 1 as the other two numbers in the third example in the second case, making 9 the median? In which case, it wouldn't be sufficient. I would imagine the two cases together give you at least two ages, allowing you solve the equation you created initially, which in turn, yields a median. I'm a little confused.

If we made 9 and 1 the other

gmat-admin - September 29, 2017

If we made 9 and 1 the other two values in the third example (for statement 2), then the three numbers would be {1, 9, 10}, in which case the average would NOT equal 10 (one of the given conditions).

I see the way you did it.

Gabriel Bellovin - February 7, 2019

I see the way you did it. When i answered it though I thought they were each insufficient because there were 2 unknowns, but then combined it was easy to determine the 3rd age and then definitively answer the target question.

Yes, that's an easy trap to

gmat-admin - February 7, 2019

Yes, that's an easy trap to fall into :-)

Cheers,
Brent

I wish this test wasn't all

Gabriel Bellovin - February 7, 2019

I wish this test wasn't all about trying to trick us!

Ha! Yes, it certainly seems

gmat-admin - February 7, 2019

Ha! Yes, it certainly seems that way at times!!

Cheeky. So very cheeky. Fell

vedavarunn - May 18, 2019

Cheeky. So very cheeky. Fell for the trap and went with C!

It's an enticing answer

gmat-admin - May 18, 2019

It's an enticing answer choice!!

Hi brent,

vishvendra - June 12, 2020

Hi brent,
I have learned that in arithmetic sequence the mean is always equal to median if its in odd number of sequence please correct me if i am wrong

You're partially correct.

gmat-admin - June 12, 2020

You're partially correct.
For ALL sequences in which the values are EQUALLY SPACED, the mean = the median.
It doesn't matter whether we have an odd or even number of values.
For example, in the set {3, 8, 13, 18}, the mean = the median = 10.5

This is covered in the following video: https://www.gmatprepnow.com/module/gmat-statistics/video/804

By the way, the GMAT doesn't expect students to know the term "arithmetic sequence."

Cheers,
Brent

Darn it Brent, made the

jonwukamuche - November 27, 2020

Darn it Brent, made the mistake of choosing C. Great question.

Also, thanks for this comment. In your previous video, there was a reinforcement question that heeded to this rule which you explained in your gmat club solution but definitely had no idea how to solve without that rule.

Question: Ages of Ann, Bea and Cho