The mean of your sampling distribution of means is 0 its sta

The mean of your sampling distribution of means is 0, its standard error = 10. What is the probability of getting a sample with mean of 25 or more when the n = 400. .4938 .5 .0062 .06

Solution

As we are already given standard error, we don\'t divide it bys sqrt(n) anymore.

We first get the z score for the critical value. As z = (x - u) / s, then as          
          
x = critical value =    25      
u = mean =    0      
          
s = standard deviation =    10      
          
Thus,          
          
z = (x - u) / s =    2.5      
          
Thus, using a table/technology, the right tailed area of this is          
          
P(z >   2.5   ) =    0.006209665 = 0.0062 [ANSWER, OPTION 3]