Question

Norma drives her car for 150 min at 40 km/h, then rests for 75 min, and then drives for 3.15 h at 60 km/h. What was Norma’s average speed?

Answer 1

Norma’s average speed is 41.9 km/h.

Step-by-step explanation:

The average speed is given by:

`\overline{v} = (d_(T))/(t_(T))`

Where:

`d_(T)`: is the total distance

`t_(T)`: is the total time

We can find the total distance as follows:

`d_(T) = v_(1)*t_(1) + v_(2)*t_(2) = 40 (km)/(h)*150 min*(1 h)/(60 min) + 60 (km)/(h)*3.15 h = 289 km`

Now, the total time is:

`t_(T) = t_(1) + t_(2) + t_(3) = 150 min*(1 h)/(60 min) + 75 min(1 h)/(60 min) + 3.15 h = 6.9 h`

Hence, the average speed is:

`\overline{v} = (d_(T))/(t_(T)) = (289 km)/(6.9 h) = 41.9 km/h`

Therefore, Norma’s average speed is 41.9 km/h.

I hope it helps you!