Confidence intervals for true population mean-sample size

Reference no: EM1318789

1) A researcher wishes to estimate the proportion of executives who own a car phone. She wants to be 90% confident and be accurate within 5% of the true proportion. Find the minimum sample size necessary.

2) A survey of 30 adults found that the mean age of a person's primary vehicle is 5.6 years. Assuming that the standard deviation of the population is .8 year, find a 99% confidence interval of the population mean age. Write a sentence that interprets this interval.

Reference no: EM1318789

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