Mary goes into labor at her local grocery store and is rushed to a hospital in an ambulance traveling 60mph. Her husband Don drives after the ambulance at an average speed of 30mph. Mary reaches the hospital fifteen minutes later. How long does it take Don to get there from the store?  Options.
A) 25 minutes	B) 30 minutes	C) 10 minutes	D) 15 minutes	E) 7 minutes

Rationale: distance covered by the ambulance in 15 minutes = 15 miles 60 mph is one mile per minute , therefore 30 mph will be 1 / 2 a mile per minute . so , he reaches the hospital half an hour after leaving the store . correct answer : b
Answer: B