Question

On a morning walk, three persons step off together and their steps measure 40 cm, 42 cm and 45 cm, respectively. What is the minimum distance each should walk, so that each can cover the same distance in complete steps?

• A. 2500 cm
• B. 2550 cm
• C. 2520 cm
• D. 2505 cm

Answer 1

The correct option is C 2520 cm

The minimum distance that they need to walk is given by the LCM of 40, 42 and 45.
$40=2\times 2\times 2\times 5$
$42=2\times 3\times 7$
$45=3\times 3\times 5$

LCM $(40,42,45)$
$=2\times 3\times 5\times 2\times 2\times 3\times 7$
$=30\times 12\times 7=210\times 12=2520$

Minimum distance each should walk is 2520 cm so that each can cover the same distance in complete steps.