A) 0.477 B) 0.155 C) 0.023 D) 0.345 20) Suppose that the average country song le

Question

A) 0.477 B) 0.155 C) 0.023 D) 0.345 20) Suppose that the average country song length in America is 4.78 minutes with a standard deviation 20) of 1.10 minutes. It is known that song length is not normally distributed. Find the probability that a single randomly selected song from the population will be less than 4.20 minutes. Round to the nearest thousandth. A) This probability cannot be determined because we do not know the distribution of the population. B) 0.006 C) 0.068 D) 0.494 21) Which of the following statements is true about the t-distribution? 21) A) For large sample sizes, the t-distribution has the same properties as the normal curve. B) Like the Normal distribution, the t-distribution is symmetric for small n. C) For small sample sizes, the t-distribution has the same properties as the normal curve. D) Since population standard deviation is usually unknown, the standard error uses the sample standard deviation to estimate population standard deviation. the following information to answer the question. Many couples believe that it is getting too expensive to hos rage" wedding in the United States. According to the website www.costofwedding.com, the average cost of a ding in the U.S. in 2009 was $24,066. Recently, in a random sample of 40 weddings in the U.S. it was found th ge cost of a wedding was $23,224, with a standard deviation of S2,903. On the basis of this, a 95% confiden val for the mean cost of weddings in the U.S. is $22,296 to $24,152. 22) Does the confidence interval provide evidence that the mean cost of a wedding has decreased? 22) A) Yes B) No

Explanation / Answer

Ans:

20)

Option A is correct.

Probability distribution is not known,so can not determine probability.

21)

Larger the sample size,the distribution approaches to the shape of a normal curve,because standard error of mean decreases.

Option A is correct.

For larger sample sizes,t distribution has the same properties as the normal curve.

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