Question

I drive at an average speed of 30 miles per hour to the railroad station each morning and just catch my train. On a particular morning there was no traffic and at the halfway point I found I had averaged 60 miles per hour. How fast must I drive for the rest of the way to catch my train exactly without having to wait for the train ?

Answer 1

20?

Answer 2

Oh, that easy ?

Answer 3

Yeah that works ! how about this one :

Next day, there was a lot of traffic and at the halfway point I found I had averaged only 15 miles per hour. How fast must I drive for the rest of the way to catch my train ?

Answer 4

\(\frac{D}{30} = T\) (T is time spent)
\(T_1 + T_2 = T\)

\(\frac{1/2}{60} + \frac{1/2}{S} = \frac{1}{30}\)

Answer 5

Nice!

Answer 6

Go fast!!

Answer 7

How fast

Answer 8

speed should be +infinity .