Which of the following statements are true? a) The sample mean is an unbiased estimate of the population mean. b) The z-critical value is an estimate of the population mean. c) The t-critical value is an estimate of the population standard deviation. d) The sample standard deviation is an unbiased estimate of the population standard deviation. e) None of the above.

Answer:e) None of the above.Step-by-step explanation:a) The sample mean is an unbiased estimate of the population mean.False. Population mean can be estimated with a margin of error around the sample mean in a specified confidence levelb) The z-critical value is an estimate of the population mean. False. z value is a conversion of values in standard normal distributionc) The t-critical value is an estimate of the population standard deviation.False. Similar to z-score t-value is a conversion in t-distribution.d) The sample standard deviation is an unbiased estimate of the population standard deviationFalse. It is a biased estimate.