The minimum sample size needed to estimate a population mean within 2 units with a 95% confidence when the population standard deviation equals 8 is OA. 9 B. 62 C. 61 A random sample of 64 observations has a mean of 30. The population variance is assumed to be 9. The 85.3% confidence interval estimate for the population mean to the third decimal place) is A. (28.560,31.440) B. (29.456, 30.544) C. (28.369, 31.631) D. (29.383.30.617)