You are given the sample mean and the population standard deviation. Use this information to construct the 90% and 95% confidence intervals for the population mean. Interpret the results and compare the widths of the confidence intervals. From a random sample of business days, the mean closing price of a certain stock was $. Assume the population standard deviation is $. The 90% confidence interval is ( nothing, nothing). (Round to two decimal places as needed.) The 95% confidence interval is ( nothing, nothing). (Round to two decimal places as needed.) Which interval is wider? Choose the correct answer below

Complete Question

The  complete question is shown on the first uploaded image

The 90% confidence interval is  

The  95%  confidence interval is

The  correct option is  D

Step-by-step explanation:

From the question we are told that

    The sample size is  n =  48

     The sample  mean is  

    The standard deviation is  

Considering first question

  Given that the confidence level is  90% then the level of significance is mathematically represented as

The  critical value  of   from the  normal distribution table is  

Generally the margin of error is mathematically represented as

The  90% confidence interval is  

=>    

=>    

Considering second question

  Given that the confidence level is  95% then the level of significance is mathematically represented as

The  critical value  of   from the  normal distribution table is  

Generally the margin of error is mathematically represented as

The  95% confidence interval is  

=>    

=>    

d no solution

step-by-step explanation:

df =

both have same length