<PRE><B>Question 211430</B>
A train travels at an average speed of 20 mph through urban areas, 
50 mph through suburban areas, and 
75 mph through rural areas. 
If a trip consists of traveling half an hour through urban areas, 
3-1/2 hours through suburban areas,
and 3 hours through rural areas, 
what is the train’s average speed for the entire trip?
;
Find the distance of the trip (dist = speed * time)
:
Total dist = urban dist + suburb dist + rural dist
d = (20*.5) + (50*3.5) + (75*3)
d = 10 + 175 + 225
d = 410 mi
:
Find the total time:
t = .5 + 3.5 + 3 
t = 7 hrs
:
Av speed = {{{d/t}}} 
s = {{{410/7}}}
s = 58.57 mph
;
:
Check solution, find the dist: 7 * 58.57 = 409.99 ~ 410</PRE>