in order to estimate the mean amount of time computer users spend on the interne

Question

in order to estimate the mean amount of time computer users spend on the internet each month how many computer users must be surveyed in order to be 90% confident that your sample mean is within 10 minutes of the population mean? assuming that the standard deviation of the population of monthly time spent on the internet is 195 min.what is a major obstacle to getting a good estimate of the population mean.use technology to find the estimated minimum required sample size.round up to the nearest whole number.

b) what is the major obstacle to getting a good estimate of the population mean

Explanation / Answer

Solution:-

Suppose a sample of size n must be drawn in order find a 95% Confidence Interval with a max error of Estimate E=10 for the mean amount of time spend on Internet ( ) .
=> E = 15, where E = margin of error,
S.D. = = 195
S.E. = / n = 195 / n
Z = 1.645 at 90% confidence.
also, E = S.E. * Z = 10
=> 195 × 1.645 / n = 10
=> n = 195 × 1.645 / 10 = 32.0775
=> n = 1028.966 or 1029 (approx.)

Ans: the Sample size necessary is 1029.

The major obstacle to getting a good estimate of the population mean is that there may not be 1029 cpmputer users to survey.

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