statistic question

[gmat]

does anyone know how to do this?

[RonPurewal]

please follow the forum guidelines, as quoted in the 'sticky' at the top of the thread:

4) Only use image files for complicated diagrams or other things that cannot easily be typed in (eg, geometric shapes or seriously complex fractions). It takes significantly longer for us to download and view image files - the more we have to do that, the fewer problems we can get through.

please transcribe this problem into the forum, and then we'll answer it.

thanks.

[Guest]

Five pieces of wood have an average (arithmetic mean) length of 124 centimeters and a median length of 140 centimeters. What is the maximum possible length, in centimeters, of the shortest piece of wood?

a. 90
b. 100
c. 110
d. 130
e. 140

OA is B.

I tried to solve it by first figuring out the total length of all five woods.

T=total

T/5= 124
total = 620

90 90 [b]140 150 150

So the shortest piece of wood is 90. The question didn't say that you can't have 2 pieces of wood with the same length.


I just don't understand why the OA is B.

[MJ]

Because you want the longest possible cm for the shortest string, you have to make the longer strings the shortest they can possibly be, all 140.

So you have strings with lenghts 140, 140, 140 (median), x and y

140 times three is 420. 620 minus 420 is 200. 200 divided by 2 is 100, so x and y can both be one hundred and this would be the greatest possible lenght of the shortest string.

[Guest]

Thanks for your response! that makes it alot clearer. I just forgot about the Maximum length and I just tried to find the shortest length of the wood. I got confused from the wording...but thanks again! Now I understand

[RonPurewal]

Thanks for your response! that makes it alot clearer. I just forgot about the Maximum length and I just tried to find the shortest length of the wood. I got confused from the wording...but thanks again! Now I understand

that tends to be the hardest part of most questions like this one.

just keep this general fact in mind: if you want to make one thing EXTREME (max or min), then you normally need to accomplish that by making other quantities EXTREME as well, usually in the other direction. for instance, if you want to maximize one thing in a set, that usually entails minimizing the other things in the set.

stated on a forum like this one, that probably sounds like common sense, but it's good to commit to memory so you'll still have it at your disposal when your nerves are wracked .

[StaceyKoprince]

Hi, guys - please follow the posting guidelines. Your subject line should be the first 5 to 8 words of the problem. Thanks!