HELP ME PLEASE

Question 3 [Total 10 marks] (a) Consider the following discrete probability distribution. W=3 X 2 4 7 9+W P(X) 0.5 0.15 0.25 0.1 Find the variance. (Correct your final answer to 1 decimal place) (3 marks) (b) Based on past records, a lecturer knows that 85% of students will pass a test. Suppose a random sample of 10 students is selected. Find the following probabilities and correct your final answers to 4 decimal places. (i) More than one selected students fail the test. (3 marks) (ii) At most 6 students pass the test given that at least 3 students failed the test. (4 marks)