Confidence interval of population mean and true proportion

• Jan 28th 2009, 05:04 PM
infamous
Confidence interval of population mean and true proportion
these 2 questions really has gotten me stumped because there isn't a given standard deviation.. can anyone help me out? here they are...

1)A study found that average time it took a person to find a new job was 5.9 months. If a sample of 36 job seeker was surveyed, find the 95% confidence interval of the population mean. Round your final answer to one decimal.

2)A survey of 80 recent fatal traffic accidents showed that 46 were alcohol-related. Find the 95% confidence interval of the true proportion of fatal alcohol-related accidents. Round our final answer to two decimals.

• Jan 28th 2009, 05:16 PM
mr fantastic
Quote:

Originally Posted by infamous
these 2 questions really has gotten me stumped because there isn't a given standard deviation.. can anyone help me out? here they are...

1)A study found that average time it took a person to find a new job was 5.9 months. If a sample of 36 job seeker was surveyed, find the 95% confidence interval of the population mean. Round your final answer to one decimal.

2)A survey of 80 recent fatal traffic accidents showed that 46 were alcohol-related. Find the 95% confidence interval of the true proportion of fatal alcohol-related accidents. Round our final answer to two decimals.