A man travels from A to B at 70 mph over a certain journey and returns over the same route to A, at 80 mph. What is his average speed for the journey?
a) 74.66 b)75 c)74.33 d)74.99 7.

• it is solve 2*x*y/x+y
  2*70*80/150=74.66
  
• 12 years agoHelpfull: Yes(8) No(0)
• avg speeed= total distance/total time
  total distance=d+d=2d
  total time=d/70+d/80=d(1/70+1/80)
  solving
  we 2*70*80/(70+80)=74.66
• 12 years agoHelpfull: Yes(4) No(0)
• formula 2*x*y/(x+y)
  so,here
  avg. speed=2*70*80/(70+80)=74.66.
  a) is correct.
• 12 years agoHelpfull: Yes(2) No(0)