An auto race consists of 8 laps. A driver completes the first 3 laps at an average speed of 185mi/h and the remaining laps at an average speed of 200mi/h.

Question

anonymous · Answer

So what's the question?

hoblos · Answer

??

across · Answer

I guess he's just trying to brag about how good he is at car racing.

anonymous · Answer

the question is, what is the average speed for the course

anonymous · Answer

Well, you should just find the mean of 185 and 200 right?

anonymous · Answer

and the answer is NOT
$$\frac{185+200}{2}$$

anonymous · Answer

oh.....

anonymous · Answer

certainly not

anonymous · Answer

i guess he needs the average speed

anonymous · Answer

what about a weighted arithmetic mean?

anonymous · Answer

yes, that is what you want.  of course i am only guessing at the question, since one was not actually asked

anonymous · Answer

thats what the safest guess is

anonymous · Answer

Let d represent the length of one lap. Write an expression in terms of d that represents the time in hours that it takes the driver to complete the race

anonymous · Answer

since 
$$d=rt$$ you would have 
$$t=\frac{d}{r}$$ have a rate of 185, 5 have a rate of 200 so i suppose you could write 
$$t=\frac{3d}{185}+\frac{5d}{200}$$

anonymous · Answer

Thanks!

anonymous · Answer

yw