Find an estimate of the sample size needed to obtain the specified margin of error for the 95% confidence interval of a population mean.
A medical researcher wishes to estimate the mean systolic blood pressure of heart surgery patients the day following surgery. She desires a margin of error of 2.2 mmHg. Past studies suggest that a population standard deviation of 42 mmHg is reasonable. Estimate the minimum sample size needed to estimate the population mean with the stated accuracy.
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