A man jogs at 6 mph over a certain journey and walks over the same route at 4 mph. What is his average speed for the journey?
a) 2.4 mph b) 4.8 mph c) 4 mph d) 5 mph

• simple formula
  2xy/(x+y)= (2*6*4*)/(6+4)= 4.8 mph
• 14 years agoHelpfull: Yes(12) No(1)
• Take one speed as s1=6mph and another speed is s2=4mph.
  Now, the average speed of the journey = (2*s1*s2)/(s1+s2)=(2*6*4)/(6+4)=48/10=4.8.
  Hence, option 'b' is correct.
• 14 years agoHelpfull: Yes(5) No(0)
• 4.8
• 14 years agoHelpfull: Yes(2) No(0)
• Average speed = (jogging speed + walking speed)/2 = (6+4)/2 = 5 mph
  so, option is 'd'
• 14 years agoHelpfull: Yes(0) No(25)