The average of n consecutive integers are taken by a student but he missed a number and get the average for (n-1) as 263/13. Find the missing no

• (n(n+1)/2 -x)/(n-1)=263/13
  put n=40 you will get x=31
• 7 years agoHelpfull: Yes(2) No(3)
• sum(1)=n*(n+1)/2 ,as 1 is the first number.
  if number 1 is taken out the sum will be sum(2)=(n-1)*average=(n-1)*263/13
  original average range will be(38.46 , 42)
  as (n-1) divisible by 13, the number n will be 40
  so, the missing number is=sum(1)-sum(2)=(40*41)/2 - (39*263)/13=31
  
  
  
• 7 years agoHelpfull: Yes(0) No(12)
• (n(n+1)/2 - x)/(n-1) = 263/13. try to have denominator (n-1) as multiple of 13 like n=14, n=27 we will not get any solution (x
• 7 years agoHelpfull: Yes(0) No(2)