Questions: A group of 49 randomly selected students has a mean age of 22.4 years with a population standard deviation of 3.8.
Use this sample data to construct a 98% confidence interval for the mean age of all students.
Transcript text: A group of 49 randomly selected students has a mean age of 22.4 years with a population standard deviation of 3.8.
Use this sample data to construct a 98\% confidence interval for the mean age of all students.
Solution
Solution Steps
Step 1: Determine the Appropriate Distribution
Given that the population standard deviation is known and the sample size is 49, we use the Z-distribution.
Step 2: Calculate the Standard Error (SE)
The standard error (SE) is calculated as SE = \(\frac{std_dev}{\sqrt{sample_size}}\) = 0.543.
Step 3: Find the Critical Value
The critical value for a 98% confidence level with Z-distribution is 2.326.
Step 4: Calculate the Margin of Error (ME)
The margin of error (ME) is calculated as ME = critical value × SE = 1.263.
Step 5: Construct the Confidence Interval
The 98% confidence interval for the population mean is (21.14, 23.66).
Final Answer: The 98% confidence interval for the population mean, rounded to 2 decimal places, is (21.14, 23.66).