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June 30th, 2012, 12:50 PM   #1
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Please help answer as many of these questions as possible!

(1) Brand Henry is a stone products salesman. Let x be the number of contacts he visits on a particular day. The following table gives the probability distribution of x.
x 1 2 3 4
P(x) 0.12 0.25 0.56 0.07
Let y be the total number of contacts Brad visits on two randomly selected days. Write the probability distribution of y.


(2) A study has shown that 20% of all college textbooks have a price of $100 or higher. It is known that the standard deviation of the prices of all college textbooks is $7.50. Suppose the prices of all college textbooks have a normal distribution. What is the mean price of all college textbooks?


(3) According to a May 27, 2009 Minneapolis Star-Tribune article, 78% of U.S. households have at least one credit card. Find the probability that in a random sample of 500 U.S. households, 375 to 385 households have at least one credit card.


(4) A machine at Keat Corporations fills 64-ounce detergent jugs. The probability distribution of the amount of detergent in these jugs is normal with a mean of 64 ounces and a standard deviation of 0.4 ounce. The quality control inspector takes a sample of 16 jugs once a week and measures the amount of detergent in these jugs. If the mean of this sample is either less than 63.75 ounces or greater than 64.25 ounces, the inspector concludes that the machine needs an adjustment. What is the probability that based on a sample of 16 jugs, the inspector will conclude that the machine needs an adjustment?


(5) Gluten sensitivity, which is also known as wheat intolerance, affects approximately 15% of people in U.S. Let p be the proportion in a random sample of 800 individuals who have gluten sensitivity. Find the probability that the value of p is

(a) Within 0.02 of the population proportion
(b) Not within 0.02 of the population proportion
(c) Greater than the population proportion by 0.025 or more
(d) Less than the population proportion by 0.03 or more [14 marks]
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June 30th, 2012, 02:46 PM   #2
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Re: Please help answer as many of these questions as possibl

Post at least a crack at each, eh? Or at least explain what is confusing you about each question.
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June 30th, 2012, 07:18 PM   #3
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Re: Please help answer as many of these questions as possibl

2.) Is the mean ? going to be greater than or less than $100? How can you find the number of standard deviations between $100 and ??

Answer these questions, and we will be well on our way...
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