Question

Consider the formula d = rt, where d represents distance, r represents rate, and t represents time. How could the formula be rearranged to determine the number of hours it takes to reach Kate's destination?
A) t=d/r
B) t=r/d
C) t=rd
D) t=dr

Answer 1

Answer: (A) t = d/r

Explanation:

You can arrive at this answer algebraically, as well as by reasoning:

Algebraic:

d = rt    | divide both sides by r. Note that r must never equal 0.

d/r = t

t = d/r --> choice (A)

Reasoning:

* the (time) must be proportional to (distance), i.e., the longer the distance the more time it will take.

* the (time) must be indirectly proportional to the (rate/speed), i.e., the faster Kate is moving the less time it will take her to the destination.

The two above are reflected in (A) and only in (A). You can apply a check to the remaining (B) - (D) choice to see that they do not satisfy the two logical expectations.