A train covers the first 60km of its journey at a speed of 80km/h the next 90 km at a speed of 100km/h and the rest of its 330-km journey at a speed of 120km/h. find the total time taken to complete it's journey. also find its average speed

Asked by babulabishoyee | 17th Oct, 2019, 05:35: AM

Expert Answer:

begin mathsize 16px style We space know space that comma
Time space equals space fraction numerator Distance over denominator Speed space end fraction
straight T subscript 1 space equals space 60 over 80 space equals space 0.75 space hrs
straight T subscript 2 space equals space 90 over 100 space equals space 0.9 space hrs
straight T subscript 3 space equals space 330 over 120 space equals space 2.75 space hrs
Total space time space taken space to space complete space the space journey space space space straight T subscript 1 space plus space straight T subscript 2 space plus space straight T subscript 3 space equals space 0.75 space plus space 0.9 space plus space 2.75 space space equals space 4. space 4 space hrs
Average space Speed space equals space fraction numerator 80 space plus space 100 space plus space 120 over denominator 3 end fraction space equals space space 100 space km divided by hr
end style

Answered by Yasmeen Khan | 17th Oct, 2019, 11:54: AM