3. A person is rock climbing at an altitude of 800 m. He go up by 7 mph, and come down by 9 mph. What was his average speed? a) 7.875mph b) 7.125 mph c) 7 mph d) 7.5 mph

• Average speed= 2xy/(x+y).
  x=7,y=9
  for confusing only he gives altitude. so
  Average speed= 2*7*9/16=7.875
  option a
• 12 years agoHelpfull: Yes(5) No(0)
• a)7.875mph
  Expln:
  Let x and y be the speed of up and down.
  Diff of speed(y-x) = 2mph
  Avg speed = 2xy / x+y
  = 2 *9*7 / (9+7) = 7.875
• 12 years agoHelpfull: Yes(3) No(0)
• His average speed is,
  2*x*y/(x + y)
  so,
  2*7*9/(7 + 9) = 7.875 mph
• 9 years agoHelpfull: Yes(2) No(0)
• by using the average speed, average speed = 2xy/(x+y)
  so here, x=7 and y=9
  average speed = 2*7*9/16=
  7.875
  so ans is option a
• 7 years agoHelpfull: Yes(0) No(0)