Question

In a morning walk, three friends step off together. Their steps measure 80 cm, 85 cm and 90 cm respectively. Find the minimum distance each friend should walk so that all can cover the same distance in complete steps.

• A. 95 m
• B. 122.4 m
• C. 105.5 m
• D. 56 m

Answer 1

The correct option is B 122.4 m

In this case we have to find the L.C.M.

$\begin{array}{cc}2& 80,85,90\\ 2& 40,85,45\\ 2& 20,85,45\\ 2& 10,85,45\\ 3& 5,85,45\\ 3& 5,85,15\\ 5& 5,85,5\\ 17& 1,17,1\\ & 1,1,1\end{array}$
L.C.M. of 80 cm, 85 cm and 90 cm
$=2\times 2\times 2\times 2\times 3\times 3\times 5\times 17$
=12240 cm =122.4 m