If Jeff drives at three fourth of his usual speed, he covers a certain distance in 3 hours more than the time he takes while driving at his usual speed. Find the time taken by him to cover this distance with his usual speed.


Answer:

9 hours

Step by Step Explanation:
  1. Let us assume that Shweta drives at a usual speed of S km/hr and takes t hours to cover a certain distance.

    According to the question,
    If, speed =  

    3
    4
      × S km/hr
    Time = t + 3 hours
  2. We know that the distance travelled in both the cases remains same.

    Also, Distance = Speed × Time

    So, S × t =  

    3
    4
      × S × (t + 3)
    ⇒ St =  
    3
    4
     S(t + 3)
    ⇒ St =  
    3
    4
     St +  
    9
    4
     S
    ⇒ St -  
    3
    4
     St =  
    9
    4
     S
    ⇒  
    1
    4
     St =  
    9
    4
     S
    ⇒ t = 9
  3. Thus, the time taken by her to cover the distance with usual speed is 9 hours.

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