Determining sample size using cofident

Reference no: EM1319092

Q1) Company that produces electronic components knows that standard deviation of lifetimes of those components is 100 hours. Company wishes to estimate mean lifetimes of components with the error that will not exceed 20 hours.

How large sample size must be taken to be

a) 95% confident;

b) 99% confident, in their estimates?

Q2) Mean and standard deviation of random sample of 90 rivet heads produced by a company are 1.8451 mm and 0.0015 mm respectively. Determine a 99% confidence interval for mean diameter of all rivet heads manufactured by company. Also determine a 95% confidence interval for standard deviation of diameter of all rivet heads manufactured by company. Give your answers correct to four decimal places.

Reference no: EM1319092

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