A consignment of 7 refrigerator sets contains 5 sets with no scratch on them. A hotel makes a random purchase of 3 of the sets. If X is the number of refrigerator sets purchased with a scratch on it,...

A consignment of 7 refrigerator sets contains 5 sets with no scratch on them. A hotel makes a random purchase of 3 of the sets. If X is the number of refrigerator sets purchased with a scratch on it, a) Find the probability distribution of X. b) Find the Cumulative Distribution Function (CDF) of X. c) Construct a graph of the CDF. d) Using CDF, find P(0
b) If U and V are two independent standard normal random variables and Z=0.6U+0.8V. Determine Corr (U , Z) iii) On the basis of a survey of 25 random typists, a confidence interval for the mean time needed to complete typing a page was (5.588; 6.412). Knowing that the distribution of the time needed to type a page is normal, and the sample standard deviation was equal to 1, determine the confidence level used for the calculations.