time, rate and distance

Question

a group of storm chasers is following behind a tornado in order to film it. The tornado is moving a straight line at 53 km per hour, and the storm chasers are driving in a van in its wake, travelling 90 km per hour. How long will it be before the van is 4 km behind the tornado.

I did not understand this question, and how to solve it. The question says that at present the van is in in the wake of tornado and they are behind. Storm chasers are moving faster than the tornado. Is this question correct? or am I reading it differently?

Answer 1

You are reading it correctly, they are driving faster to catch up. You don't have enough information to solve the question, though. You need how far behind they start out.

Answer 2

Even though you can't get a number (as Ross pointed out), you can write an equation.

If the goal is to be $4$ km behind, and the van closes in at $90 - 53 = 37$ km/hour, then the time will be $t = (d-4)/37$, where $t$ is measured in hours and $d$ is the starting distance away from the tornado.