A state police officer is chasing a car he believes is speeding. The officer is traveling at 70mph to try and catch up with the car. But he can't say later that the other car was going 70mph because the driver could ask, "If we were going the same speed, how did you catch up? Obviously I was going slower than you. I wasn't speeding." The officer sees the driver pass a mile marker, one-fourth of a mile ahead. From the marker, it takes the officer five minutes (1/12 of an hour) to catch up. How fast was the driver going


How do I solve this difficult problem??

Okay, first ignore the fact that the officer is going at 70mph.

Pretend that the officer is going some fixed speed, and the car he is chasing isn't moving at all. Could you now work out the speed the officer is going?

How does this answer relate to the original problem? What is the answer to your original problem? :)

Let me know if this helped -- :)

Pull out the radar gun man

Subtract the rates of the speeder and the cop.

This difference takes 5 minutes to cover 1/4 mile.

Since the cop is going 70, then the difference in the rates is r-70.

Since d=rt, we have

\frac{1}{4}=(r-70)\frac{1}{12}

solve for r.

THREAD CLOSED BECAUSE IT WAS REVIVED. Thanks.