We are driving along a highway at a constant speed of 55 miles per hour (mph). You observe a car one half mile behind you. The car is moving fast and zooms past you exactly one minute later. How fast is this car traveling (mph) if its speed is constant?

a. 80

b. 70

c. 72

d. 85

• 55+ 0.5*60=85 ( multipled with 60 because its 0.5 miles per minute which needs to converted to miles per hour)
• 6 years agoHelpfull: Yes(19) No(0)
• s1 is speed of 1st car
  s2 is speed of 2nd car
  from relative
  s1 - s2 = distance between car1 and car2 / time
  s1 - 55 = 0.5/(1/60)
  s1 -55 = 0.5 * 60
  s1 - 55 = 30.0
  s1 = 55 + 30
  s1 = 85 mph
  ans :- 85
• 5 years agoHelpfull: Yes(15) No(0)
• relative speed= 0.5 miles * 60 =30.0 m
  speed=(55+30)=85
• 6 years agoHelpfull: Yes(6) No(1)
• given 55 mph.. we observe a car behind us.. "car is moving exactly 1 minute faster"..
  from the quoted sentence we simply understand that the car's speeds up after a minute..therefore
  convert our speed 55 mph to miles per minute----55/60=0.916 miles/min
  then the car's speed is 0.5+our speed per minute..bcoz the time is inversely proportional to speed.
  therefore add 1 ----0.5+0.916=1.416
  then convert it to miles per hour 1.416*60=84.96````85
  thus 85 is the correct answer
• 6 years agoHelpfull: Yes(3) No(1)
• Dist= 0.5 mile since both are traveling same direction so net speed to met is x-55
  0.5÷(x-55)=1÷60
  So x=85mph
• 5 years agoHelpfull: Yes(1) No(0)
• 85 is the answer
• 6 years agoHelpfull: Yes(0) No(4)
• distance covered by car moving with v in one minute v* (1/60)
  is equal to 1/2 mile plus distance covered by car moving with 55 mph in one minute 55* (1/60)
  
  v* (1/60) = 1/2 + 55* (1/60)
  v = 30 + 55 = 85 mph
• 5 years agoHelpfull: Yes(0) No(0)
• given 55 mph.. we observe a car behind us.. "car is moving exactly 1 minute faster"..
  from the quoted sentence we simply understand that the car's speeds up after a minute..therefore
  convert our speed 55 mph to miles per minute----55/60=0.916 miles/min
  then the car's speed is 0.5+our speed per minute..bcoz the time is inversely proportional to speed.
  therefore add 1 ----0.5+0.916=1.416
  then convert it to miles per hour 1.416*60=84.96````85
  thus 85 is the correct answer
• 5 years agoHelpfull: Yes(0) No(0)
• speed =55 m
  relative speed =0.5 m
  time =60
  speed constant = s+(r.s*t)
  s c = 55+(0.5*60)
  =55 + 30
  =85
• 5 years agoHelpfull: Yes(0) No(0)
• speed of the car is 55.
  distance of both car=0.5.
  
  speed=0.5*60=30.
  now constant speed is 55+30=85.
  
  Hence answer is 85.
• 5 years agoHelpfull: Yes(0) No(0)
• as the car is coming from behind the observers car thus the speed of the car will be subtracted from the observers car .the net speed will be (x-55). the relation between speed,time and distance calulation will be as follow (x-55) = (1/2)/(1/60)
• 5 years agoHelpfull: Yes(0) No(0)
• The speed of the car is 84.96 mph
  
  Since the car is 0.5 miles away from you, and crosses you in exactly one min, which means the other car will cover 0.5 miles more in one min than your car
  
  The speed of your car is 55 mph or 0.916 miles per minuter
  
  Therefore the speed of the other car is 0.916+0.5=1.416 miles per minute
  
  Thus the speed of the other car is =1.416*60=84.96 mph
• 5 years agoHelpfull: Yes(0) No(0)