Question

Traffic on saturday, it took ms. torres 24 minutes to drive 20 miles from her home to her office. during friday's rush hour, it took 75 minutes to drive the same distance.

a. what was ms. torres's average speed in miles per hour on saturday?


b. what was her average speed in miles per hour on friday?

Answer 1

a. 50 mph.

b. 16 mph.

Explanation:

a.

Convert minutes to hours using dimensional analysis:

`\displaystyle \rm 24 \; minutes * (1\; hour)/(60\; minutes) = (2)/(5)\; hours`.

Average speed is distance traveled over time taken:

`\displaystyle \text{Average Speed} = \frac{\text{Distance Traveled}}{\text{Time Taken}} = \rm (20\; miles)/((2)/(5)\; hours) = (20 * (5)/(2))\; mph= 50\; mph`.

b.

Similarly,

`\displaystyle \text{Time Taken} = \rm 75 \; minutes * (1\; hour)/(60\; minutes) = (5)/(4)\; hours`.

`\displaystyle \text{Average Speed} = \frac{\text{Distance Traveled}}{\text{Time Taken}} = \rm (20\; miles)/((5)/(4)\; hours) = (20* (4)/(5))\; mph= 16\; mph`.