Q.

If every term of the statistical data consisting of n terms is decreased by 2, then the mean of the data:

1 decreases by 2
   
2 remains unchanged  
3 decreases by 2n  
4 decreases by 1  

Ans.

(1)

Let n terms of data be

x1,x2,x3,…,xn.∴  Mean (x¯)=∑i=1nxinNow, when each term is decreased by 2.∴Data will be x1-2,x2-2,x3-2,…,xn-2∴New mean==∑i=1n(xi-2)n=∑i=1nxin-2nn=x¯-2⇒" Mean is also decreased by 2."