1. ## speed distance problem

A bank robber holds up a bank and speeds away on the freeway at 80 miles per hour. Thirty minutes later, police officers, having gotten a description from people at the bank, take off in pursuit at 90 miles per hour. How long will the police have to drive to catch up, and how far from the bank will they catch the robber? Remember that distance=velocity*time

2. Originally Posted by jsimms
A bank robber holds up a bank and speeds away on the freeway at 80 miles per hour. Thirty minutes later, police officers, having gotten a description from people at the bank, take off in pursuit at 90 miles per hour. How long will the police have to drive to catch up, and how far from the bank will they catch the robber? Remember that distance=velocity*time
Right, so say you start the 'race' with the robber with 40 miles of a headstart (half an hour, hour is 80 miles... )
And he's travelling at 80 mph, and the cops are travelling at 90mph.

So, when are they equal?
When 80x + 40 = 90x.
Where x is the length of time , so x = 4.

So, after 4 hours after the cops have arrived the robber will have travelled 80*(4) + 40 = 360.
And the cops will have travelled 90 * 4 = 360 miles.