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Calculate the following:
a) Determine the sample size necessary to estimate a population mean to within 1 with a 90% confidence given that the population standard deviation is 10.
b) Suppose that the sample was calculated at 150. Estimate the population mean with 90% confidence.

  • Statistics -

    Formula for a):
    n = [(z-value * sd)/E]^2
    ...where n = sample size, z-value will be found using a z-table to represent the 90% confidence interval, sd = 10, E = 1, ^2 means squared, and * means to multiply.

    Plug the values into the formula and finish the calculation. Round your answer to the next highest whole number.

    For b) Use a confidence interval formula:
    CI90 = mean + or - z-value (sd/√n)

    I'll let you take it from here.

  • Statistics -


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