A straight one-mile stretch of highway is 40 feet wide. You ride your bike on a
path composed of semicircles as shown. If you ride at 5 miles per hour, how many hours will
it take you to cover the one-mile stretch?
Note: 1 mile = 5280 feet
Pick one.
A) π/11 hours	B) π/10 hours	C) π/5 hours	D) 2π/5 hours	E) 2π/3 hours
We wish to solve for t in the equation s = v t, where s is the distance covered in   feet, and v = 5 5280 feet an hour.   Note that each semicircle has a radius of 20 feet (half the width of the road). This means   that you must complete 5280=40 semicircles to cover the one-mile stretch. Each of thosesemicircles measures 20 feet. You ride then a grand total of   5280/40*20π=5280/2π   feet. We have then :   5280/2π=5*5280*t which gives t =π/10 hours   correct answer π/10 hours
<result>B</result>
A straight one-mile stretch of highway is 40 feet wide. You ride your bike on a
path composed of semicircles as shown. If you ride at 5 miles per hour, how many hours will
it take you to cover the one-mile stretch?
Note: 1 mile = 5280 feet