if Sn be the sum of first n natural number.where n>=10.then what will be the probablity of Sn-1 is divided by 72?

• Is the question correct?? I think there must be an upper limit for the n for us to have some number in the denominator.
• 10 years agoHelpfull: Yes(1) No(1)
• As it is natural no like-1,2,3,4,......upto 10.so,1st no must be 1 nd common diff-1 den Sn=n/2[2a+(n-1)*d]
  so,Sn-1=S9=10/2[2+9*1]=55. Now 55 /72 i.e having only one probability
• 10 years agoHelpfull: Yes(0) No(4)
• here Sn is not sum of first natural no .Sn is sum of suqare of first n natural number.
• 10 years agoHelpfull: Yes(0) No(0)