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1) (a) For which binomial distribution would a normal approximation be most acce

ID: 3155679 • Letter: 1

Question

1) (a) For which binomial distribution would a normal approximation be most acceptable? (A) n=50, pi=0.05 (B) n=100, pi=0.04 (C) n=40, pi=0.25 (D) n=400, pi=0.02

(b) Concerning confidence intervals, which statement is most nearly correct? (A) we should use z instead of t when n is large (B) we use the studen'ts t distribution when standard deviation is unknown (C) we use the students t distribution to narrow the confidence interval

(c) A discrete probability distribution: (A) is a listing of all possible values of the random variable (B) assigns a probability to each possible value of the random variable (C) can assume values between -1 and +1 (D) is independent of the parameters of the distribution

Explanation / Answer

1) (a) For which binomial distribution would a normal approximation be most acceptable?

Here, we need that n p and n (1-p) are both at least 10. It only happens for

OPTION (C) n=40, pi=0.25 [ANSWER, C]

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(b) Concerning confidence intervals, which statement is most nearly correct?

By convention, and by central limit theorem,

(A) we should use z instead of t when n is large [ANSWER, OPTION A]

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(c) A discrete probability distribution:

By definition,

OPTION (B) assigns a probability to each possible value of the random variable [ANSWER, B]