Answer:
30.2 is the answer (use distrubutyion in this problem)
Step-by-step explanation:
 
        
             
        
        
        
Answer:
(47.3, 54.1)
Step-by-step explanation:
We have that to find our  level, that is the subtraction of 1 by the confidence interval divided by 2. So:
 level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of  .
.
That is z with a pvalue of  , so Z = 1.96.
, so Z = 1.96.
Now, find the margin of error M as such

In which  is the standard deviation of the population and n is the size of the sample.
 is the standard deviation of the population and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 50.7 - 3.4 = 47.3
The upper end of the interval is the sample mean added to M. So it is 50.7 + 3.4 = 54.1
The answer is (47.3, 54.1).
 
        
             
        
        
        
Answer:
18h
Step-by-step explanation:
 
        
             
        
        
        
-45x+72
you multiply the 9 by everything in the parentheses