Answer :
Answer:
85.5 km/h
Explanation:
[tex]t_{1}[/tex] = time interval for first phase = 14 min = [tex]\frac{14}{60}[/tex] h = 0.233 h
[tex]t_{2}[/tex] = time interval for second phase = 46 min = [tex]\frac{46}{60}[/tex] h = 0.767 h
[tex]v[/tex] = average speed for the entire trip = 74 km/h
[tex]v_{1}[/tex] = average speed in first phase = 36 km/h
[tex]v_{2}[/tex] = average speed in second phase
[tex]d_{1}[/tex] = distance traveled in first phase
[tex]d_{2}[/tex] = distance traveled in first phase
average speed is given as
[tex]v = \frac{d_{1} + d_{2}}{t_{1} + t_{2}}[/tex]
[tex]v = \frac{v_{1} t_{1} + v_{2} t_{2}}{t_{1} + t_{2}}[/tex]
[tex]74 = \frac{(36) (0.233) + v_{2} (0.767)}{0.233 + 0.767}[/tex]
[tex]74 = (36) (0.233) + v_{2} (0.767)[/tex]
[tex]v_{2} = 85.5[/tex] km/h