1. ## Speed of Train

The trip from Manhattan to Montauk Point is 120 miles by train or by car. A train makes the trip in 2 hours, while a car makes the trip in
5/2 hours. How much faster, in miles per hour, is the average speed of the train than the average speed of the car?

2. Originally Posted by magentarita
The trip from Manhattan to Montauk Point is 120 miles by train or by car. A train makes the trip in 2 hours, while a car makes the trip in
5/2 hours. How much faster, in miles per hour, is the average speed of the train than the average speed of the car?

The general formula is:

$\displaystyle average\ speed = \dfrac{complete\ distance}{elapsed\ time}$

Thus

$\displaystyle v_{train}=\dfrac{120\ mi}{2\ h}= 60 \dfrac{mi}h$

$\displaystyle v_{car}=\dfrac{120\ mi}{\frac52\ h}= 48 \dfrac{mi}h$

Therefore the train is $\displaystyle 12\ \frac{mi}h$ faster than the car.

3. ## ok...

Originally Posted by earboth
The general formula is:

$\displaystyle average\ speed = \dfrac{complete\ distance}{elapsed\ time}$

Thus

$\displaystyle v_{train}=\dfrac{120\ mi}{2\ h}= 60 \dfrac{mi}h$

$\displaystyle v_{car}=\dfrac{120\ mi}{\frac52\ h}= 48 \dfrac{mi}h$

Therefore the train is $\displaystyle 12\ \frac{mi}h$ faster than the car.