Question

Irina rode her bike to work at an average speed of 16 miles per hour. It started to rain, so she got a ride home along the same route in her coworker’s car at an average speed of 27 miles per hour. If Irina’s ride home in the car took 24 minutes (0.4 of an hour), how many hours was her bike ride to work, to the nearest tenth of an hour?

Answer 1

Average speed of Irina riding home in her coworkers car = 27 miles per hour
Time taken by Irina to reach home = 0.4 hour.
Then
In 1 hour the car traveled for a distance = 27 miles
So in 0.4 hour, the distance traveled by the car = 27 * 0.4 miles
                                                                           = 10.8 miles
Now
While traveling to office, Irina travels 16 miles in = 1 hour
So
Irina travels 10.8 miles in = (16/10.8) hours
                                         = 1.48 hours.]
So Irina takes 1.48 hours of bike riding to reach her place of work.

Answer 2

Answer:

0.7 hours

Explanation:

From the way back, we can calculate the distance between Irina's work and Irina's home. In fact, we know that the car takes 0.4 hourse traveling at 27 mph, so the distance covered should be

$d=vt=(27 mph)(0.4 h)=10.8 mi$

When Irina rides to work with her bike, she travels at a speed of 16 mph. So we can find the time she takes by dividing the total distance (10.8 miles) by her speed:

$t=\frac{d}{v}=\frac{10.8 mi}{16 mph}=0.7 h$