Can you explain how to solve such type of statistics questions?

It would be great help if you can explain variation of such questions as well.

Let X1, ...; Xis be a random sample from a normal distribution with unknown mean & and known variance o' = 81. A sample ], . . . , @16 is collected and the sample mean from this sample is calculated to be a = 8. Based on this sample, a 95% confidence interval for / is Select one: O (3.59,12.41) O (8,00) O (-00, 8) O (0,8) Let X1, .... Xis be a random sample from a normal distribution with unknown mean & and known variance o = 12. Consider the following hypotheses: Ho : / = 10, H1 : / > 10. A sample #1, . . .,15 is collected and the sample mean from this sample is calculated to be r = 12. The test statistic > and p-value p for testing these hypotheses (UMP) based on this sample are: Select one: O = = 2.33, p = 1% O z = -2.24, p = 1.25% O z = 2.24, p = 2.50% O z = 2.24, p = 1.25%