Question

A train travels the first 15 km at a uniform speed of 30 km/h; the next 75 km at a uniform speed of 50 km/h; and the last 10 km at a uniform speed of 20 km/h. Calculate the average speed for the entire train journey.

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Answer 1

Explanation:

First 15km at a uniform speed of 30km/h

Next 75km at a uniform speed of 50km/h

Last 10km/h at a uniform speed of 20km/h

Time 1st=15/30

Time 2nd=75/50

Time 3rd=10/20

Total Time= 15/30+75/50+10/20

Total Time=5/2

Total Distance=100km

Average Speed =40km/h

Answer 2

Answer:

Given:-

${d}^{1} = 15km \: {v}^{1} = 30km \: h$

${d}^{2} = 75km \: {v}^{2} = 50 km \: h$

${d}^{3} = 10km \: {v}^{3} = 20km \: h$

we know that,

we know that, average speed =total distance covered/total time taken

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km total time taken =T=(15/30)+(75/50)+(10/20)=2.5hours

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km total time taken =T=(15/30)+(75/50)+(10/20)=2.5hoursso, average speed =100/2.5=40km/h

Answer 3

Answer:

Given:-

${d}^{1} = 15km \: {v}^{1} = 30km \: h$

${d}^{2} = 75km \: {v}^{2} = 50 km \: h$

${d}^{3} = 10km \: {v}^{3} = 20km \: h$

we know that,

we know that, average speed =total distance covered/total time taken

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km total time taken =T=(15/30)+(75/50)+(10/20)=2.5hours

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km total time taken =T=(15/30)+(75/50)+(10/20)=2.5hoursso, average speed =100/2.5=40km/h

Answer 4

Answer:

Given:-

${d}^{1} = 15km \: {v}^{1} = 30km \: h$

${d}^{2} = 75km \: {v}^{2} = 50 km \: h$

${d}^{3} = 10km \: {v}^{3} = 20km \: h$

we know that,

we know that, average speed =total distance covered/total time taken

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km total time taken =T=(15/30)+(75/50)+(10/20)=2.5hours

we know that, average speed =total distance covered/total time taken total distance covered =D=15+75+10=100km total time taken =T=(15/30)+(75/50)+(10/20)=2.5hoursso, average speed =100/2.5=40km/h