Answer:
A. The standard deviation of the sampling distribution of x is o / √n, where o is the standard deviation and n is the sample size.
o = 5.2
n = 9 
5.2/√9 
1.733333333 
 
B. To solve this problem, we take the same formula from part A and work backwards, solving for n, the sample size. 
2.6 = 5.2/√n 
(2.6)√n = 5.2 
√n = 5.2/2.6 
√n = 2 
n = 4 
 
Step-by-step explanation:
This formula sheet: