iMyself wrote:In an electric circuit, two resistors with resistances x and y are connected in parallel. In this case, if r is the combined resistance of these two resistors, then the reciprocal of r is equal to the reciprocal of the sum of x and y. What is r in terms of x and y ?
(A) xy
(B) x + y
(C)1/(x + y)
(D) xy/(x + y)
(E) (x + y)/xy
I received a PM requesting my input.
The reciprocal of r is equal to the reciprocal of the sum of x and y.
1/r = 1/(x+y).
Cross-multiplying, we get:
x+y = r.
The correct answer is
B.
The problem posted above is an altered version of an official problem in the OG16.
The original problem -- which is trickier -- can be found here:
https://www.beatthegmat.com/reciprocals-t84790.html
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