Question: Ages of Ann, Bea and Cho

Comment on Ages of Ann, Bea and Cho

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.
gmat-admin's picture

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. 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.
gmat-admin's picture

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

Cheers,
Brent

I wish this test wasn't all about trying to trick us!
gmat-admin's picture

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

Cheeky. So very cheeky. Fell for the trap and went with C!
gmat-admin's picture

It's an enticing answer choice!!

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
gmat-admin's picture

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

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