A multiple choice test consists of 9 questions with 5 choices for each answer. A

Question

A multiple choice test consists of 9 questions with 5 choices for each answer. Assume that a student guesses all questions randomly. The random variable, X, is the number of correct guesses. The correct distribution for X is A. N(9, 5) B. N(9, 0.2) C. B(9, 0.2) D. T_8 Find the probability that the student guesses no more than 3 questions correct? A. 0.0856 B. 0.3333 C. 0.9144 D. 01762 Over the long run of taking such an exam, on average how many questions would you expect a student to get correct by guessing randomly on each question of the test? A. 1 B. 2 C. 1.8 D. 2.2 Cardiac pacemaker batteries will stop working if they are not properly calibrated and chained. Suppose that the length of time a battery operates follows a normal distribution with a mean and standard deviation of 25.0 days. Find the first quartile of this distribution. A. 7.19 days B. 0.11 days C. 6.25 days D. 8.14days Find the probability that a randomly selected cardiac pacemaker batteries lasts at least 25.8 days. A. 0.6205 B. 0.4872 C. 0.3795 D. 0.6437 Suppose the length of time a pacemaker battery lasts is collected for a sample of 49 batteries. Find the distribution for the average length of time a battery operates for the sample of 49 batteries. A. N(25, 25) B. N(25, 3.57) C. Exp (0.51) D. Exp(25) Find the probability that the average time a sample of 49 batteries lasts is no more 24.7 days. A. 0.5335 B. 0.4665 C. 0.6277 D. 0.3723

Explanation / Answer

36. B(9,0.2) option C

37. P(X<4)=0.9144 option C

38. 2 option B

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