商务统计学章节测试课后答案2024春

第五章测试

1.Variables which take on values only at certain points over a given interval are called _______.
A:value variables B:point variables C:continuous random variables D:discrete random variables
答案:D
2.A variable that can take on values at any point over a given interval is called _______.
A:a continuous random variable B:a point variable C:a value variable D:a discrete random variable 3.You are offered an investment opportunity. Its outcomes and probabilities are presented in the following table. XP(X)–$1000.40$0.20+$1000.40 The mean of this distribution is _____________.
A:$400 B:$200 C:–$400 D:$0 4.You are offered an investment opportunity. Its outcomes and probabilities are presented in the following table. XP(X)–$1000.40$0.20+$1000.40 The standard deviation of this distribution is _____________.
A:$663 B:$800,000 C:–$400 D:$894 5.The long-run average or mean of a Poisson distribution is usually referred to as _______.
A:s B:a C:l D:m 6.The variance of a Poisson distribution is equal to _______.
A:l B:l2 C: D:l/2 7.If X is a binomial random with n = 8 and p = 0.6, what is the probability that X is less than or equal to 2?
A:0.050 B:0.375 C:0.009 D:0.041 8.If X is a binomial random with n = 8 and p = 0.6, what is the probability that X is greater than 2?
A:0.011 B:0.124 C:0.950 D:0.991 9.Twenty-five items are sampled. Each of these has the same probability of being defective. The probability that exactly 2 of the 25 are defective could best be found by _______.
A:using the binomial distribution B:using the normal distribution C:using the Poisson distribution D:using the exponential distribution 10.You are offered an investment opportunity. Its outcomes and probabilities are presented in the following table. XP(X)–$1000.40$0.20+$1000.40 Which of the following statements is true?
A:This is a binomial distribution. B:This distribution is skewed to the left. C:This distribution is symmetric. D:This distribution is skewed to the right.