In a test , there were n number of question. In the test `2^(n - i)` students gave wrong answers to i number of question , where i = 1, 2, 3,......, n. If the total number of wrong answer of wrong answer given is 2047, then n is

If the ratio of the total number of combinations of 2n different things to the total number of combinations of n different things be 1025 : 1 , find n .

If s(n)= i^n+i^(-n) where i=sqrt(-1) and n is an integer then the total number of distinct values of S(n) is

There are natural numbers. Answer the following questions considering first natural numbers. Variance of first n natural numbers is -

There are natural numbers. Answer the following questions considering first natural numbers. Mean of first n natural number is -

If the mean of the set of numbers x_1,x_2, x_3, ..., x_n is barx, then the mean of the numbers x_i+2i, 1 lt= i lt= n is

In n is a natural number,n(n + 1)(n + 2) will always divisible by

There are natural numbers. Answer the following questions considering first natural numbers. Mean of square of first n natural numbers is -

Answer the following questions in short: Show that if n numbers are drawn at random without replacement from the set (1, 2, 3, ..., N), then var (barX) = ((N+1)(N-n))/(12n) .

Nitu and Milan sat for a Competitive examination on a science subject today. There were 12 questions in the question paper. 6 marks was allotted for each correct answer and 3 marks for each wrong answer. Nitu had 7 correct answers and got 5 answers wrong.