Quiz_11_Solutions - Quiz 11 Name: _ December 4, 2009...

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Quiz 11 Name: _____________________________ December 4, 2009 Studies have shown that 22% of all orders from Amazon.com are from first-time customers. A simple random sample of 90 orders is taken to estimate the proportion of first-time customers to see if this is actually true. a. What are the sampling distribution and parameters of p ? ~ =. , =. -. = . p Normalμ 22 σ 221 2290 0 044 b. What is the probability the proportion of first-time customers in 2009 is more than 25%? >. = >. -. . = - . = . Pp 25 PZ 25 220 044 1 Φ0 68 0 248 c. What is the probability the proportion of first-time customers in 2009 is within 5% of the population proportion, 22%? . < <. = - . . < < . . = . - - . = . P 17 p 27 P 0 050 044 Z 0 050 044 Φ1 14 Φ 1 14 0 746 ~ = , = x Normalμ EX σ2 VarXn xi ~ = , = Normalμ nEX σ2 nVar X ~ = = , = - p Normalμ xn p σ2 p1 pn
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Quiz 11 Name: _____________________________ December 4, 2009 It has been reported that in the United States, 44% of senior citizens are now using the internet. A sample
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This note was uploaded on 03/27/2012 for the course STAT 225 taught by Professor Martin during the Fall '08 term at Purdue University-West Lafayette.

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Quiz_11_Solutions - Quiz 11 Name: _ December 4, 2009...

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