SOLUTION: Hi If speed is increased by 20 percent a person arrives 15 minutes early. What is the initial time taken by the person. Thanks

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Question 1186798: Hi
If speed is increased by 20 percent a person arrives 15 minutes early. What is the initial time taken by the person.
Thanks
Found 2 solutions by MathLover1, ikleyn:
Answer by MathLover1(20850)   (Show Source): You can put this solution on YOUR website!
the initial time
the initial speed
if speed is increased by percent :

time reduced min








->the initial time taken by the person

Answer by ikleyn(52790)   (Show Source): You can put this solution on YOUR website!
.
If speed is increased by 20 percent, a person arrives 15 minutes earlier.
What is the regular time taken by the person.
~~~~~~~~~~~~~~~~~ 


Let  "d"  be the distance, let "t" be the regular (= the scheduled) travel time (in minutes), and let "u"  be the regular speed. 

Then the increased speed is  1.2u, and reduced traveled time is  t-15 minutes.


We have two equations

     = t              (1)

and

     = t - 15    (2)


From equation (2), we have

     = 1.2*(t-15).


In this equation, replace its left side    by  t, based on equation (1).  
You will get then simple linear equation for the single unknown t


    t = 1.2*(t-15).


Simplify and find t

    t = 1.2t - 18

    18 = 1.2t - t

    18 = 0.2t

     t =  =  = 90 minutes.


ANSWER.  The regular (=the scheduled) travel time is 90 minutes.

Solved.



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