Two independent samples of sizes 11 and 8 are randomly selec…

Two independent samples of sizes 11 and 8 are randomly selected from two normal populations with two equal but unknow variances.   Which of the following distributions should be used for developing confidence intervals and for testing hypotheses about the difference between the two population means

A die shows up numbers one to six with probabilities 0.1, 0….

A die shows up numbers one to six with probabilities 0.1, 0.1, 0.1, 0.1, 0.2, 0.4, respectively.  Roll the die four times independently. It is known that for i=1,2,3 4, the number i is not observed in the i-th roll.  What is the probability of getting the number 5 once and the number 6 once.