kamalakarthi wrote:Hi Experts,
Thanks all for helping by answering the doubts. The below question is from Manhattan CAT.
Even though, I got to the right answer by back solving the answers, I could not get to the right choice immediately by solving thru equations.
My equations considering R is the rate and T is the time :
(R-4). (T+16)= 96
1.5 R * T = 96
so I tried to equate
Why cant I equate like the below
(R-4). (T+16) = 1.5 R * T
You have to eliminate a variable in order to solve the equation. When you equated that way, you left yourself without a way to eliminate a variable.
But, when I tried 96/R-4 = 96/1.5r +16, I was able to solve. It took time to come to this way so how should I approach these questions during setting up the equation.
The key here is to see that you have to eliminate a variable in order to solve.
It is often the case that in doing an algebraic translation in the process of answering a GMAT quant question, you are best off eliminating a variable in creating the setup if possible.
For instance, in an age question involving the ages of three people, you may be able to express the ages of two people in terms of the age of the third person. So, if it were the case that you could do so, you could set up the equations for answering the question by using just one variable.
In this case, the key to getting the right answer is to see that you can eliminate T in the process of setting up. When you do so, you are left with only one variable, R.