Answer :
The 90% confidence interval for the mean hours to meet course objectives is about 789.9 to 816.1 hours, based on a sample mean of 803 and standard deviation of 51.7 from 42 students.
The formula for calculating the confidence interval for a population mean with a known standard deviation is given by:
Confidence Interval = Mean ± (Z * (Standard Deviation / √Sample Size))
In this case, you have:
Mean = 803
Standard Deviation = 51.7
Sample Size = 42
Z-value for a 90% confidence level ≈ 1.645
Substitute these values into the formula:
Confidence Interval = 803 ± (1.645 * (51.7 / √42))
Now calculate the values:
Confidence Interval = 803 ± (1.645 * (51.7 / 6.4807))
Confidence Interval = 803 ± 13.1342
Rounded to one decimal place:
Confidence Interval ≈ (789.9, 816.1)
So, the 90% confidence interval for the mean number of hours it takes for a student to meet the course objectives is approximately (789.9, 816.1) hours.
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