Answer:
(a) The sample size required is 43.
(b) The sample size required is 62.
Step-by-step explanation:
The (1 - α) % confidence interval for population mean is:
The margin of error for this interval is:
(a)
The information provided is:
<em>σ</em> = 4 minutes
MOE = 72 seconds = 1.2 minutes
Confidence level = 95%
α = 5%
Compute the critical value of z for α = 5% as follows:
*Use a z-table.
Compute the sample size required as follows:
Thus, the sample size required is 43.
(b)
The information provided is:
<em>σ</em> = 4 minutes
MOE = 1 minute
Confidence level = 95%
α = 5%
Compute the critical value of z for α = 5% as follows:
*Use a z-table.
Compute the sample size required as follows:
Thus, the sample size required is 62.
