Delivery order of desk chairs...Prep 2 Math

[tim]

:)

[asharma8080]

Is there a way to do this problem and look at B without making the algebraic equation. I used plugging in for A, and then tried similar approach for B but did not work. I essentially could not form the equation 10 + (n-1) / n = 1.36 but I see it now. I am just wondering if there is a more logical way to think about B than trying to use the equation?

[jlucero]

Is there a way to do this problem and look at B without making the algebraic equation. I used plugging in for A, and then tried similar approach for B but did not work. I essentially could not form the equation 10 + (n-1) / n = 1.36 but I see it now. I am just wondering if there is a more logical way to think about B than trying to use the equation?

Absolutely. Think of it this way:

1 chair costs $10 = $10/chair
2 chairs costs $11 = $5.50/chair
3 chairs costs $12 = $4/chair
....

Now if I saw this question on the real GMAT, I'm not calculating out these numbers on paper, but I do want to recognize that for every additional chair that I purchase, the cost per chair goes down. Which means that at some point, the average cost per chair has to match up with $1.36/chair. If this were a PS question, I'd have to solve, but in this case, I want to recognize that there has to be just one solution, hence sufficient. It's the same logic as noticing the single variable equation and knowing there must be a solution, but in a more "real world" sense (IMO, at least).