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.

Step-by-step explanation

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

40 minutes =
`(40)/(60)hours =(2)/(3) hours` and 23 minutes =
`(23)/(60)hours`

Now,
`Distance = Speed* Time`

So, the distance traveled for first 40 minutes at 88 km/hr speed
`=(88* (2)/(3))km = 58.67 km` ,

the distance traveled for next 40 minutes at 75 km/hr speed
`=(75*(2)/(3))km=50 km` and

the distance traveled last 23 minutes at 49 km/hr speed
`=(49*(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)
`=((127.45)/(2))km/hr = 63.725 km/hr =64 km/hr` (Rounded to the nearest km/hr)