Question

If you drive 30 miles in 40 minutes, and then 15 miles in 20 minutes, do you have a constant speed?

A) yes

B) no

C) maybe, depending on the instantaneous speed at each instant of the trip

D) maybe, depending on the car

Answer 1

Answer:

A) yes

Explanation:

First section of trip: 30 miles in 40 minutes

Second section of trip: 15 miles in 20 minutes

The formula for speed is distance over time $k=\frac{d}{t}$

Calculate the speeds for each section of the trip.

First:

k = d/t

k = 30miles/40minutes  <= reduce fraction by 10 (30÷10 and 40÷10)

k = 3 miles / 4 minutes

Second:

k = d/t

k = 15miles/20minutes  <= reduce fraction by 5 (15÷5 and 20÷5)

k = 3 miles / 4 minutes

Therefore there is a constant speed because both sections of the trip are driving at "3 miles / 4 minutes".

3 miles / 4 minutes can be also formatted as:

0.75 miles per minute.