Question

In a morning walk four boys steps off together. Their steps measure 70 cm , 65 cm , 75 cm and 80 cm respectively . At what distance from the starting point will they step off together again?

Answer 1

The distance covered by each one of them is required to be same and minimum. The required minimum distance each should walk must be the LCM of their steps in cm.

$70=2\times 5\times 7$

$65=5\times 13$

$75=3\times 5\times 5$

$80=2\times 2\times 2\times 2\times 5$

$LCM=2\times 2\times 2\times 2\times 3\times 5\times 5\times 7\times 13=109200$

They will step off together again after a distance of 109200 cm =1092 m