A motor car starts with a speed of 70 kmph with its speed increasing for every two hours

A motor car starts with a speed of 70 kmph with its speed increasing for every two hours by 10 The time taken to cover 360 kms is

  1. 4 hours 20 minutes
  2. 4 hours 30 minutes
  3. 4 hours 40 minutes
  4. 4 hours 50 minutes
Anurag Mishra Professor Asked on 20th April 2016 in Maths.
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1 Answer(s)

Answer: (3) 4 hours 40 minutes 

Solution:-
Distance covered in first 2 hours = (70 x 2) km = 140 km
Distance covered in next 2 hours = (80 x 2) km = 160 km
Remaining distance = 360 – (140 + 160) = 60 km.
Speed in the fifth hour = 90 km/hr
Time taken to cover 60 km =(60/90) hr = (2/3) hr
Therefore Total time taken = 2 + 2 + (2/3) = 4 (2/3)hrs 
Then, the time taken to cover 360 kms is 4 hours 40 minutes. 

Hence, the correct answer is option (3)  4 hours 40 minutes. 

Anurag Mishra Professor Answered on 21st April 2016.
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