Let X be the height of a randomly chosen individual from a population. In order to estimate the mean and variance of X, we observe a random sample X, X,,X7. Thus, X's are i.i.d. and have the same distribution as X. We obtain the following values (in centimeters): 166.8, 171.4, 169.1, 178.5, 168.0, 157.9, 170.1 Find the values of the sample mean, the sample variance, and the sample standard deviation for the observed sample.