Respuesta :
Pauline's average speed for this trip is 64 km/hr.
Explanation
First we will convert each 'minutes' into 'hours' . So......
40 minutes = [tex]\frac{40}{60}hours =\frac{2}{3} hours[/tex] and 23 minutes = [tex]\frac{23}{60}hours[/tex]
Now, [tex]Distance = Speed* Time[/tex]
So, the distance traveled for first 40 minutes at 88 km/hr speed [tex]=(88* \frac{2}{3})km = 58.67 km[/tex] ,
the distance traveled for next 40 minutes at 75 km/hr speed [tex]=(75*\frac{2}{3})km=50 km[/tex] and
the distance traveled last 23 minutes at 49 km/hr speed [tex]=(49*\frac{23}{60})km = 18.78 km[/tex]
So, the total distance traveled [tex]=(58.67+50+18.78) km = 127.45 km[/tex]
She spends 17 minutes eating lunch and buying gas.
So, the total time taken for the trip [tex]= (40+40+17+23)minutes = 120 minutes= 2 hours[/tex]
Thus, Pauline's average speed for this trip = (Total distance / Total time) [tex]=(\frac{127.45}{2})km/hr = 63.725 km/hr =64 km/hr[/tex] (Rounded to the nearest km/hr)
