Homework#6

# Homework#6 - Suppose approximately 80 of OSU students are...

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Stat 133 Autumn 2007 NAME Allison Heck Homework #6 (10 points) GROUP #_________ Due Thursday Nov 8 (beginning of recitation) 1. Which of the following is NOT a discrete random variable? a. The time between accidents on a busy highway. b. The number of accidents on a busy highway. c. The number of red cars that go by, in a random sample of 100. d. All of the above are discrete random variables. 2. Assume X and Y are ANY two random variables (not necessarily independent!) Answer True or False for each one below: a. μ ( X + Y ) = ( X ) + ( Y ) TRUE FALSE b. σ ( X + Y ) = ( X ) + ( Y ) TRUE FALSE c. (4 X +5 Y ) = 4 ( X ) + 5 ( Y ) TRUE FALSE 3. Suppose ρ (X,Y) =0. Then X and Y must be independent. a. True b. False 4. What proportion of the data from a normal distribution lie within two standard deviations on either side of the mean (using the table)? a. 0.3413 b. 0.4772 c. 0.6826 d. 0.9544 5. If your value of Z is Z = .80 then you are at the 80 th percentile of the Z distribution. a. True b. False Use the following information for problems 6-8:

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Unformatted text preview: Suppose approximately 80% of OSU students are in favor of the smoking ban. Two OSU students are selected at random. 6. What is the probability that both of them support the smoking ban? P(YY) = (.8)(.8) ANS .64 7. What is the probability that both of them oppose the smoking ban? P(NN) = (.2)(.2) ANS .04 8. What is the probability that at least one of them supports the smoking ban? P(YN) + P(NY) = (.8)(.2) + (.2)(.8) ANS .32 1 Use the following information for problems 9-10: Let X be the amount of cash a customer withdraws from their account at the bank. Let X have a Normal distribution with mean \$100 and standard deviation \$25. 9. Find the 75th percentile for X. ANS \$116.75 10. Find the probability that one customer chosen at random withdraws less than \$60. M x = \$100 σ x = \$25 ANS .0548 2...
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## This note was uploaded on 02/16/2010 for the course STAT 133 taught by Professor Rumseyjohnson during the Fall '07 term at Ohio State.

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Homework#6 - Suppose approximately 80 of OSU students are...

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