Statistical question

[3] Let 5'" = (11:1) L10": - 1")2 be the sample variance. What is the expected value of 52? Is 52 an unbiased estimator for population variance? li'ii'hvr or why not? Let S be the sample standard deviation. What is the expected value of 5? Is 5 an unbiased estimator for population standard deviation? Why or why not? [4] Find an upper bound on Pi IX - ,u | 2 4} in [3] using the Chebvshev inequality. Suppose sampling distribution of sample mean with a sample size of 25 Is considered. Find an upper bound on Pi l)? ,ul 24:1 using the Chebvshev inequality