X=4 is the answer to this
Answer:
the answer is c.768
Step-by-step explanation:
Answer:
a
The point estimate of the population mean is 
b
The 80% confidence level is 
c
There is 80% confidence that the true population mean lies within the confidence interval.
Step-by-step explanation:
From the question we are told that
The sample size is n = 18
The standard deviation is 
The sample mean is 
Generally the point estimate of the population mean is equivalent to the sample mean whose value is 
Given that the confidence interval is 80% then the level of significance is mathematically represented as



Next we obtain the critical value of
from the normal distribution table
The value is 
Generally the margin of error is mathematically evaluated as

=> 
=> 
Generally the 80% confidence interval is mathematically represented as

=> 
=> 
The interpretation is that there is 80% confidence that the true population mean lies within the limit
we are given

Since, we have to solve for b

so, we will isolate b ony one side
so, we will add 60 on both sides



so,
Answer:
Maureen should have added 60 to both sides.