SAT math question (algebra)

Question

Nate walks 25 meters in 13.7 seconds. If he walks at this same rate, which of the following is closest to the distance he will walk in 4 minutes? A) 150 meters B) 450 meters C) 700 meters D) 1,400 meters

Answer 1

Using 'm' for meters and 's' for seconds, our ratio is 25 m / 13.7 s = X m / 240 s

Cross-multiplying:

X = 240 * 25 / 13.7

But 25 / 13.7 is about 2, so

X is approximately 240 * 2, or 480.

480 is closest to 450, so answer B (450 m) is the one we want.

Answer 2

First we must find his original rate that he walks. However, we have to keep the units consistent, so to prevent making an error I will convert the time to minutes.

=> 13.7 seconds * (1 min/60 seconds) = 0.2283 minutes

Using the D = r*t equation => r = D/t

r = 25 meters/0.2833 minutes

We can leave this as a fraction for now and plug it in to our next equation.

Now we want to solve for d when t = 4 minutes and r = 25 meters/0.2833 minutes (notice that the units for time are the same).

=> d = 4*(25/0.2833) = 438

This is closest to 450 meters so the answer is B.

Answer 3

4 min is approximately 16 times 13.7 min

16 times 25 is 400.

B) 400 meters