The value of `1+2+3+...+n` is
`(a) (n+1)/2`
`(b) n/2`
`(c) (n(n+1))/2`
`(d) (n^2(n+1)^2)/2`

The arithmetic mean of 1,2,3,...n is (a) (n+1)/(2) (b) (n-1)/(2) (c) (n)/(2)(d)(n)/(2)+1

The value of lim_( n to oo) ((1)/(n) + (n)/((n+1)^2) + (n)/( (n+2)^2) + ...+ (n)/( (2n-1)^2) ) is

If tan x=n tan y,n in R^(+), then the maximum value of sec^(2)(x-y) is equal to (a) ((n+1)^(2))/(2n) (b) ((n+1)^(2))/(n)( c) ((n+1)^(2))/(2) (d) ((n+1)^(2))/(4n)

The value of C_1/2+C_3/4+C_5/6+………. is equal to (A) (2^n=1)/(n-10 (B) 2^n/(n=1) (C) (2^n+1)/(n+1) (D) (2^n-1)/(n+1)

Mean deviation of the series a,a+d,a+2d,......,a+2nd from its mean is (a) ((n+1)d)/((2n+1))( b )(nd)/(2n+1) (c) ((2n+1)d)/(n(n+1)) (d) (n(n+1)d)/(2n+1)

Sum of series : 1+2+3+......... +n is (A) ((n)(n+1))/2 (B) n(n+1) (C) ((n+1)(n+2))/2 (D) none of these.

The value of 1+1.1!+2.2!+3.3!+.........+n.n! is (A) (n+1)!+1(B)(n-1)!+i(C)(n+1)!-1(D)(n+1)!

The standard deviation of the data: x : 1 a a^2 ... a^n f: ^n C_0 ^n C_1 ^n C_2 ... ^n C_n is (a)((1+a^2)/2)^n-((1+a^2)/2)^n (b) ((1+a^2)/2)^(2n)-((1+a^2)/2)^(2n) (c) ((1+a^)/2)^(2n)-((1+a^2)/2)^n (d) none of these

The arithmetic mean of the series 1,2,4,8,16,....2^(n) is (2^(n)-1)/(n+1) (b) (2^(n)+1)/(n) (c) (2^(n)-1)/(n) (d) (2^(n+1)-1)/(n+1)

If the value of (n + 2) . ""^(n)C_(0) *2^(n+1) - (n+1) * ""^(n)C_(1)*2^(n) + n* ""^(n)C_(2) * 2^(n-1) -... is equal to k(n +1) , the value of k is .