Respuesta :
Answer:
a) Standard Error = 0.6578
b) 99% confidence interval = (7.303, 10.697)
c) A population mean of 8.5 hours would not surprise the psychologist as this is within the confidence interval.
Step-by-step explanation:
a) Standard error = Standard deviation/√n
n = sample size = 250
Standard deviation = 10.4
Standard error = (10.4/√250)
Standard error = 0.6578
b) 99% confidence interval
Confidence interval = (Sample mean) ± (Margin of error)
Sample mean = 9 hours
Margin of Error = (critical value) × (standard error or standard deviation of the distribution of sample means)
Critical value for a 99% confidence interval = 2.58 (from the z-tables)
Standard error or standard deviation of the distribution of sample means = 0.6578
margin of error = 2.58 × 0.6578 = 1.697
Confidence interval = 9 ± 1.697
Lower limit of the confidence interval = 9 - 1.697 = 7.303 hours
Upper limit of the confidence interval = 9 + 1.697 = 10.697 hours
99% confidence interval = (7.303, 10.697)
c) A population mean of 8.5 hours would not surprise the psychologist as this is within the confidence interval.
Hope this Helps!!!
The standard error of the sampling distribution will be 0.6578.
How to calculate the standard error?
The standard error is simply calculated as the standard deviation divided by the square root of n. This will be:
= 10.4 / ✓250
= 0.6578
Also, the margin of error will be:
= 2.58 × (0.6578)
= 1.697
The confidence interval will be:
= (9 - 1.697)
= 7.303 hours.
Also, 9 + 1.697 = 10.697.
In conclusion, the confidence interval is (7.303, 10.697).
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