sujit2k7 wrote:

Thanks a Lot Zarrolou and Ron

BTW seems like GMAT is a playground for all RONs ( Previously It was Manhattan Ron , Now Vertisas Ron)

...I am definitely going give my son's name RON..hehehhehe( i m still unmarried )

Jokes apart can someone tell me when are the below conditions become false.... (these changes in mean , median really bug me up)

A.The mean will decrease but median will not change.

B.The median will decrease but mean will not change.

C.The range will increase but median will not change.

D.The range will increase but mean will decrease.

E.The standard deviation will increase but mean will decrease.

Hey sujit2k7, thanks for the compliment about the Rons! I'll pass it on to my parents. I tell them it stands for "Really Outstanding Name"

As for your question about when these changes become false, Zarrolou's post gives a good example of how these conditions can change with the set 2,2. All four other options (A, C, D, E) could occur in that situation. In general terms, the introduction of a new term will change the mean of a set unless the new term is exactly that mean. However a median can remain the same even if scores of new numbers are introduced.

Consider a set consisting of ten 5's {5,5,5,5,5,5,5,5,5,5}. You could add -1's until the number of terms in this set went from 10 to 19 and the set would then be {-1,-1,-1,-1,-1,-1,-1,-1,-1, 5,5,5,5,5,5,5,5,5,5}, in which case the middle term would still be 5, so the mean would remain unchanged. However as soon as you add a single -1 the mean will drop from 5 to 4.5 or so. It helps when looking at these abstract questions to try real numbers and then draw logical conclusions from your observations.

Hope this helps!

-Ron

_________________

Ron Awad

Veritas Prep | GMAT Instructor

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