If the mean deviation of the numbers `1,""1""+""d ,""1""+""2d ,""..."",""1""+""100 d` from their mean is 255, then the d is equal to (1) 10.0 (2) 20.0 (3) 10.1 (4) 20.2

If 0.13+p^(2)=13, then p equals (a) 0.01 (b) 0.1(c)10(d)100

The mean deviation of the numbers,4,5,6,7 from the mean is 25 (b) 5 (c) 1.2 (d) 0

If [[x,1]][[1,0],[2,0]]=0 ,then x equals (A) 0 (B) -2 (C) -1 (D) 2

For any 2xx2 matrix, if A\ (a d j\ A)=[10 0 0 10] , then |A| is equal to (a) 20 (b) 100 (c) 10 (d) 0

6.The mean and the standard deviation (s.d.) of 10 observations are 20 and 2 respectively.Each of these 10 observations is multiplied by p and then reduced by q ,where p!=0 and q!=0 .If the new mean and new s.d.become half of their original values, then q is equal to : (1)-10 (2) 10 (3) -5 (4) -20