Question

The time, t, required to drive a certain distance varies inversely with the speed, r, if it takes 7 hours to drive the distance at 55 miles per hour, how long will it take to drive the same distance at 65 miles per hour
A. about 6.25 hrs
B. about 385.00 hrs
C. about 5.92 hrs
D. about 3.21 hrs

Answer 1

Inverse functions will be given by the following equation:

$t * r = k$

k is a constant value that the two variables must multiply to.

Plug in your t and r values:

$7 * 55 = 385$

k = 385.

Now we'll have to find a value that multiplies with 65 to equal 365.

Set up the following equation:

$x * 65 = 385$

This equation can also be treated as the following:

$65x = 385$

Divide both sides by 385 to get x by itself:

$x = 5.92$

The answer is C. about 5.92 hrs to drive the same distance of 385 miles.