Question

Seema, Meena and Reema begin to jog around a circular stadium and they complete their revolution in $54$ seconds , $42$ seconds and $63$ seconds respectively. After approximately how many minutes will they come together at the starting point ?

• A. $8.5$ minutes
• B. $10.3$ minutes
• C. $3.9$ minutes
• D. $6.3$ minutes
• E. None of these

Answer 1

The correct option is D $6.3$ minutes

They will meet together at starting point after,
LCM of $(54,42,63)$ seconds
$54=2\times 3\times 3\times 3$
$42=2\times 3\times 7$
$63=3\times 3\times 7$
Required LCM $=3\times 3\times 3\times 2\times 7=378$ seconds $=6.3$ minutes.