Self-Doubt

Question

Q. Two consecutive numbers are removed from the progression 1, 2, 3, ...n.  The arithmetic mean of the remaining numbers is 26 1/4.  The value of n is

a. 60	b. 81
c. 50	d. Cannot be determined

Comments

Not the best way but I formed an equation and tried the options.

26.25 = (sum of 1st n natural numbers - x - x-1) / (n-2)

where the sum of 1st n natural numbers is n(n+1) / 2

x and x+1 are the two consecutive numbers subtracted from it.

n-2 because 2 numbers are removed from n.

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@gaurav

After form equation then you randomly check using value of (n , x).

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No. I tried the 3 options in place of n and tried to calculate x

Answer 1

Answer should be 50.

Comments

If you are answering, at least include the solution in it. It is already known that the answer is 50.