Question

The pupils of tenth standard of a school had arranged for a picnic at a total cost of Rs.300, which had to be shared equally by them.since 5 of them failed to join the party,each of the other had to pay Rs.2 more.Find the strength of the class.

Answer 1

Let the strength of the class be  N.      Let the cost per person be  Rs P.
Total cost = Rs  N * p = Rs 300.

As 5 of the students did not join the party,  the total cost
   Rs 300 = (N-5) * (p+2)
               = N p - 5 p + 2 N - 10
               = 300 - 5 p + 2 N - 10
   =>  5 p = 2 N - 10
   =>  5 * 300/N = 2 N - 10
  =>   N² - 5 N - 750 =  0
         (N - 30) (N + 25) = 0
           N = 30  as  N is positive.