Question 756548
Some bank robbers leave town, speeding at 100 mph 15 minutes later, the police give chase, traveling at 110 mph. How long (in hours) will it take the police to overtake the robbers? 
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In 15 mins, they're 25 miles away (100*0.25)
The cops gain on them at 10 mi/hr (110 - 100)
25/10 = 2.5 hours.
@ 110 mi/hr, that's 275 miles away.
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They should radio ahead.