Distance = Rate x Time.
The distance the officer has to make up is .2 miles.  The speed at which the officer makes up the distance is the difference between the cars' speeds.  That's 60 - 50 = 10 MPH.
.2 = 10 * t
.2/10 = t
.02 hours = t = 1.2 minutes = 1 minute 12 seconds.
Hope the solution helped.  Sometimes you need more than a solution.  Contact fcabanski@hotmail.com for online, private tutoring, or personalized problem solving (quick for groups of problems.)