Question

A fast Humvee drove from desert A to desert B. For the first 12

hours, it travelled at an average speed of 185 km/h. For the
next 13 hours, it travelled at an average speed of 160 km/h.
What was the average speed of the whole journey?
km/h

Answer 1

v = 172 km/h

Step-by-step explanation:

For the first 12 hours, it traveled at an average speed of 185 km/h. Let d₁ is distance. So,

`d_1=v_1* t_1\\\\d_1=185\ km/h* 12\ h\\\\d_1=2220\ km`

For the next 13 hours, it traveled at an average speed of 160 km/h. Let d₂ is the distance. So,

`d_2=v_2* t_2\\\\d_2=160\ km/h* 13\ h\\\\d_2=2080\ km`

Average speed = total distance/time taken

So,

`v=(d_1+d_2)/(t_1+t_2)\\\\v=(2220+2080)/(12+13)\\\\v=172\ km/h`

So, the average speed of the whole journey is 172 km/h.