If I had walked 1 km/hr faster, I would have taken 15 minutes less to walk 3 km. Find the rate at which I was walking.

Asked by arajeevshashank | 25th Jun, 2020, 11:12: AM

Expert Answer:

Let normal speed of a student be x km/h

Distance (d) = 3 km

Time = distance/speed = 3/x hours

If a student had walk 1 km/h faster then his speed would have been x + 1 km/h.

Time = 3/(x+1)

begin mathsize 16px style 3 over straight x minus fraction numerator 3 over denominator straight x plus 1 end fraction equals 15 over 60
3 open parentheses 1 over straight x minus fraction numerator 1 over denominator straight x plus 1 end fraction close parentheses equals 1 fourth
12 open parentheses fraction numerator begin display style straight x plus 1 minus straight x end style over denominator begin display style straight x open parentheses straight x plus 1 close parentheses end style end fraction close parentheses equals 1
12 equals straight x squared space plus space straight x
straight x squared space plus space straight x space minus space 12 space equals space 0
left parenthesis straight x space plus space 4 right parenthesis left parenthesis straight x space minus space 3 right parenthesis space equals space 0
straight x space equals space minus 4 space or space straight x space equals space 3
straight x space not equal to negative 4 space hence space straight x space equals space 3 space km divided by hour



end style

Answered by Renu Varma | 25th Jun, 2020, 11:34: AM