Question 364468
let the total no. of seat = x

then no. of ways by which 3 people can sit is  xP3 = 210  ( x permutation 3)

=> x!/(x-3)! = 210

=>x*(x-1)*(x-2) = 210 

=> x* (x-1) *(x-2) = 2 * 3 * 5 *7                  by factorizing 210

 =>x*(x-1)*(x-2) = 7*6*5



so, value of x is 7.


no. of seats = 7