Question

A dance competition takes place where participants take place in pairs. If during the performance they gradually form a group of four, six and nine persons, then the number of participants can be

• A. $18$
• B. $72$
• C. $54$
• D. $90$

Answer 1

The correct option is B $72$

Number of participants will be L.C.M. of $2,4,6,9$
$4=2^2$
$6=2\times 3$
$9=3^2$
L.C.M. $=2^2\times 3^2=36$
So, number of participants will be multiple of $36.$