SOLUTION: Any assistance is greatly appreciated: A runner is training for a marathon on a track whose straightaways are 500 ft and semicircles have a diameter of 40 ft. What is the total

Algebra ->  Length-and-distance -> SOLUTION: Any assistance is greatly appreciated: A runner is training for a marathon on a track whose straightaways are 500 ft and semicircles have a diameter of 40 ft. What is the total      Log On


   

Question 333722: Any assistance is greatly appreciated:
A runner is training for a marathon on a track whose straightaways are 500 ft and semicircles have a diameter of 40 ft. What is the total distance he will run if he runs the track 13 times? What is his average speed in MPH if it takes him 40 minutes and 35 seconds after 13 times?
Thank you for your time.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
length of 1 round = 500+500+ pi*40 ( 2 semicircles on either end)
=1000+40*pi
=1125.66 feet is the length of 1 lap.
13 laps will be
13 * 1125.66
=14633.62 feet
..
5280 feet = 1 mile
14633.62 feet = 146322.62/5280
= 2.77 miles
..
40 minutes 35 seconds is the time taken for 13 laps.
=2400+35
= 2435 seconds
..
2435/3600 = 0.676 hours
speed = distance / time
=2.77 miles/0.676
= 6.9 mph