Integer properties question

[maria08]

This is a Quant Comparison problem- I think I first came across this in the MGRE number properties study guide but ever since I have seen similar questions...

Column A
The mean of all positive odd integers from 1 to 50 inclusive.

Column B
The mean of all positive even integers from 2 to 50 inclusive.

I know there is some smart shortcut to this but I do not know what that is.
I've tried to learn some formulas - how to calculate the last term of a sequence or the sum of evenly-spaced integers but to my disappointment I keep forgetting the magic formula for easy calculation, it's a shame I know.

anyway, can you help, Tommy?
cheers
maria

[tommywallach]

Hey Maria,

The mean/median of any evenly spaced set is: (First + Last) / 2
(remember, the mean and the median are the same in any evenly spaced set).

So:

Column A
The mean of all positive odd integers from 1 to 50 inclusive.
(1 + 49) / 2 = 25


Column B
The mean of all positive even integers from 2 to 50 inclusive.
(2 + 50) /2 = 26

Answer is B. Easy!

-t

[maria08]

Wow, it seems very easy indeed. thanks, Tommy

[tommywallach]

Glad to help!

-t