Respuesta :
Answer:
53.53 km/h
Explanation:
Given that the person drives for 30.0 min at 80.0 km/h, 12.0 min at 105 km/h, and 45.0 min at 40.0 km/h, and he spends 15.0 min eating lunch and buying gas.
So, the total time to complete the journey is
t=30+12+45+15=102 min
[tex]=\frac{102}{60}=1.7[/tex] hours
As distance=(speed)x(time), so
the distance covered in 30 minutes with a speed of 80 km/h
[tex]d_1=80 \times \frac{30}{60}=40[/tex] km.
The distance covered in 12 minutes with a speed of 105 km/h
[tex]d_2=105 \times \frac{12}{60}=21 km[/tex].
The distance covered in 45 minutes with a speed of 40 km/h
[tex]d_3=40 \times \frac{45}{60}=30 km[/tex].
So, to the total distance covered is
[tex]d=d_1+d_2+d_3[/tex]
[tex]=40+21+30=91 km[/tex]
As the average speed = (Total distance covered)/(Total time taken)
So, the average speed for the whole journey
[tex]=\frac{d}{t}[/tex]
[tex]=\frac{91}{1.7}= 53.53 km/h[/tex].
Hence, the average speed for the trip is 53.53 km/h.
