Question

An airplane flies 1500 miles in 2 hours and 46 minutes. What is its average speed in miles per hour? (rounded to the nearest tenth)
a. 543.4

b. 543.48

c. 541.6

d. 54.148

Answer 1

The average speed in miles per hour is 541.6 miles/hr.

Answer: Option C

Explanation:

Average speed is defined as the rate of change in the distance per unit time. So the ratio of distance covered by a vehicle in a specified time gives the average speed at which the vehicle or the object is moving. As in the present case, the air plane has covered 1500 miles in 2 hrs and 46 minute. So the formula for calculating average speed is given below.

            $\text {Average speed}=\frac{\text { Distance covered }}{\text { Time taken }}$

So as the distance covered is 1500 miles and time taken is 2 hrs and 46 min, the average speed will be

           $\text {Average speed}=\frac{1500 \mathrm{miles}}{2 \mathrm{hrs} 46 \mathrm{min}}$

As we need the answer in miles per hour, so no need to convert the units of distance but the units of time should be converted to hours. As $1 \min =\frac{1}{60}$ hr, we get

$\text { Average speed }=\frac{1500 \text { miles }}{\left(2+\left(\frac{46}{60}\right)\right) h r s}=\frac{1500 \text { miles }}{(2+0.77) h r}=\frac{1500 \text { miles }}{2.77 h r}$

So,

             $\text { Average speed }=541.6 \text { miles /hr }$