Question 3 In a random sample of forty-eight 200-metre swims has a mean time of 3.12 minutes and a standard deviation of 0.09 minutes. (a) Construct the 89% confidence interval for the population mean time. (b) If all the other quantities remain the same, how does the indicated change affect the width of the confidence interval? (i) Increase in the sample size (ii) Increase in the level of confidence.
Question 3
In a random sample of forty-eight 200-metre swims has a mean time of 3.12 minutes and a standard deviation of 0.09 minutes.
(a) Construct the 89% confidence interval for the population mean time.
(b) If all the other quantities remain the same, how does the indicated change affect the width of the confidence interval?
(i) Increase in the
(ii) Increase in the level of confidence.
Question 4
In a sample of 400 shops it was discovered that 136 of them sold carpets at below the list prices, which had been recommended by manufacturers.
(a) Estimate the percentage of all carpet selling shops below list price.
(b) Calculate the 95% confidence limits for this estimate.
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