Question

A car can average 20 km per hour up a hill, and 60 km per down the same road. What is the average speed for the whole trip ?

Answer 1

The average speed of the whole trip is 40km/hr.

• The speed of the car in the uphill direction = 20km/hr

The speed of the car in the downhill direction = 60km/hr

• Now we have to calculate the average speed of the whole trip by using the following formula

(Downhill speed+uphill speed)/2 [ we divide the total by 2, because the total phase of the total journey is also 2]

• Now,the average speed

= (20+60)/2

= 80/2

= 40 km/hr

The average speed of the whole trip is 40 km/hr. (Answer)

Answer 2

The required average speed is 40 km/hr

It is given that,

The speed of the car when it goes up a hill = 20 km/hr

Speed of the car when it comes down a hill = 60 km/hr

To find : The average speed for the whole trip.

To find the average speed, we have to add the individual speeds and then divide it by 2

So,

$\frac{60 + 20}{2}$

$\frac{80}{2}$

$40 \: km \: per \: hour$