Question

Pauline travels between two cities. First she drives for 40 minutes at an average speed of 88 km/hr then for 40 minutes at an average speed of 75 km/hr, then she spends 17 minutes eating lunch and buying gas, and then she drives for 23 minutes at an average speed of 49 km/hr. Find pauline's average speed for this trip. Express it in kilometers per hour and round your answer to the nearest km/hr.

Answer 1

Pauline's average speed for this trip is 64 km/hr.

Explanation

First we will convert each 'minutes' into 'hours' . So......

40 minutes = $\frac{40}{60}hours =\frac{2}{3} hours$ and 23 minutes = $\frac{23}{60}hours$

Now,  $Distance = Speed* Time$

So, the distance traveled for first 40 minutes at 88 km/hr speed $=(88* \frac{2}{3})km = 58.67 km$ ,

the distance traveled for next 40 minutes at 75 km/hr speed $=(75*\frac{2}{3})km=50 km$ and

the distance traveled last 23 minutes at 49 km/hr speed $=(49*\frac{23}{60})km = 18.78 km$

So, the total distance traveled $=(58.67+50+18.78) km = 127.45 km$

She spends 17 minutes eating lunch and buying gas.

So, the total time taken for the trip $= (40+40+17+23)minutes = 120 minutes= 2 hours$

Thus, Pauline's average speed for this trip = (Total distance / Total time) $=(\frac{127.45}{2})km/hr = 63.725 km/hr =64 km/hr$ (Rounded to the nearest km/hr)