ICSE Class 7 Answered

In down-stream a man went 18 km at a speed of 6 km/hr and in up-stream he came back the same distance at a speed of 3 km/ hr. Find the average speed for whole journey.

Asked by Topperlearning User | 19 Sep, 2016, 10:30: AM

Expert Answer

$Total space distance space covered space equals space 2 cross times 18 space equals space 36 space km. Time space taken space to space go space 18 space km space at space straight a space speed space of space 6 space km divided by space hr space equals Distance over Speed equals 18 over 6 equals space 3 space hr. Time space taken space to space go space 18 space km space at space straight a space speed space of space 3 space km divided by space hr space equals Distance over Speed equals 18 over 3 equals space 6 space hr. Total space time space taken space equals space 3 space hr space plus space 6 space hr space equals space 9 space hr therefore space Average space speed space equals space fraction numerator Total space distance over denominator Total space time end fraction equals 36 over 9 equals 4 space km divided by hr The space average space speed space of space the space whole space journey space is space 4 space km divided by hr.$

Answered by | 19 Sep, 2016, 12:30: PM

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ICSE Class 7 Answered

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