A person who decided to go weekend trip should not exceed 8 hours driving in a day average speed of forward journey is 40 mph due to traffic in Sundays the return journey average speed is 30 mph. How far he can select a picnic spot.

• His average speed will be 2*40*30/(30+40) = 240/7 mph
  
  so max distance of picnic point will be (240/7)*8/2= = 960/ 7 kms
• 13 years agoHelpfull: Yes(14) No(5)
• Average speed =2ab/(a+b)
  a=40mph
  b=30mph
  simplifying we get 240/7
  
  speed=distance/time
  
  
  we have average speed=240/7
  
  time=8/2 =4. because 8hrs=(going+coming)
  
  equating for distance we get d=s*t d=240/7*4= 137.14
  Therefor he cannot choose a distance which is greater than 137.14, so the answer is
  a) 120 miles
• 11 years agoHelpfull: Yes(7) No(0)
• max. journey in forward= 8h*40mph= 320m
  max in return journey on sunday= 30mph*8h=240m
  for selecting the picnic spot take the average distance =
  max. during forward+ max.during return
  =(320m+240m)/2
  =280m
  
  hence solved...........:-)
• 11 years agoHelpfull: Yes(0) No(3)
• average speed=2*x*y/(x+y)
  here, x=40 and y=30
  putting value of x and y in equation we get,
  average speed=2*30*40 /(30+40) =240/7
  ans: 240/7
• 7 years agoHelpfull: Yes(0) No(0)