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manigraja100
Students
 
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Joined: Sun Mar 03, 2013 12:00 am
 

Algebra.Pg 167.#13

by manigraja100 Mon Jun 24, 2013 12:53 am

The stiffness of a diving board is proportional to the cube of its thickness and inversely proportional to the cube of its length.If diving board A length is twice as long as diving board B and has 8 times the stiffness of diving board B,what is the ratio of the thickness of diving board A to that of diving board B ?
I was stumped by this question until i saw the explanation as to pick nos for thickness and length.I understood the problem.But how to know that we have to pick nos for particular variable,like why didn't we picked nos for stiffness ? is there any strategy that can help me with this ?
tommywallach
Manhattan Prep Staff
 
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Re: Algebra.Pg 167.#13

by tommywallach Wed Jun 26, 2013 6:54 pm

Hey Mani,

Honestly, there's really only one logical way to do it. If you try it any other way, it just doesn't work (or else it's really complicated). This will always be the case when doing questions for which one wants to/ought to plug in. Logic will always send you in a certain direction. It's partially in the way they write the questions, and partially in getting experienced enough with correct plug-in solutions to know which way you ought to go first. What I can tell you for certain is that I never plug in for the "wrong thing." I may occasionally fail to notice that I ought to plug in, but you said you understood that element of it.

Hope that helps!

-t