In series of 2n observations, half of them equal a and remaining half equal -a. If the standard deviation of the observation is 2, then |a| equals

Question

In a series of 2n observations, half of them equal a and remaining half equal – a. If the standard deviation of the observations is 2, then |a| equals 

(a) 2 

(b) √2 

(c) 1/n 

(d) √2/n.

Answer 1

(a) : According to question, we have