Stat_Final_Review_Supplementalsp10

A b whatistheprobabilitythatthesumisatleast4 0 c d 1

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Unformatted text preview: de on a randomly selected day by a small clothing store on Main Street. Assume X is Normal with a mean of $360 and a standard deviation of $50. 47. What is P(X > $400)? A) 0.2119 C) 0.7881 B) 0.2881 D) 0.8450 48. The probability is approximately 0.6 that on a randomly selected day the store will make less than how much? A) $0.30 C) $361.30 B) $347.40 D) $372.60 49. Bicycles arrive at a bike shop as parts in a box. Before they can be sold, they must be unpacked and assembled. Based on past experience, the bike shop owner knows that assembly times follow (roughly) a Normal distribution with a mean of 25 minutes and a standard deviation of 3 minutes. A customer walks into the bike shop and wishes to buy a bike like the one in the window, but in a different color. The shop has one, but it is still in the box, so it will need to be assembled. What is the probability that the bike will be ready within a half hour? A) 0.0478 C) 0.8413 B) 0.1587 D) 0.9522 50. Consider the following three scenarios and determine if the random variable described in each is either discrete or continuous. I. – The increase in length of life of a cancer patient following chemotherapy. II. – The volume of gasoline lost due to evaporation during the filling of a gas tank. III. – The number of cracks that exceed 1.5 centimeters in 10 kilometers of a major highway. The random variable in scenarios I, II, and III, respectively, is: A) Continuous, discrete, discrete. B) Continuous, continuous, discrete. C) Continuous, continuous, continuous. D) Discrete, continuous, discrete. E) Discrete, discrete, continuous. 11 J Diaco Elements of Statistics I Supplemental Final Exam Review 51. A) B) C) D) E) The following table describes the probability distribution for the random variable X that counts the number of times a customer visits a grocery store in a 1‐week period: Visits 0 1 2 3 4 or more P(Visits) 0.1 0.25 0.3 ? 0.1 The value of the entry in the table for 3 Visits should be: 0.2 0.55 0.75 0.25 0.35 Use the following to answer questions 52–54: Suppose there are three balls in a box. On one of the balls is the number 1, on another is the number 2, and on the third is the number 3. You select two balls at random and without replacement from the box and note the two numbers observed. The sample space S consists of the three equally likely outcomes {(1, 2), (1, 3), (2, 3)} (disregarding order). Let X be the sum of the two balls selected. 52. A) Which of the following is the correct distribution for X? Value of X 1 2 3 Probability 3 4 5 ⅓ ⅓ ⅓ Value of X 1 2 3 Probability 1 Value of X 3 Probability D) ⅓ Probability C) ⅓ Value of X B) ⅓ 1 6 6 2 6 4 2 6 3 6 5 3 6 53. A) B) What is the probability that the sum is at least 4? 0 C) ⅔ ⅓ D) 1 54. A) B) What is the mean of X? 2.0 2.33 C) D) 4.0 4.33 12 J Diaco Elements of Statistics I Supplemental Final Exam Review 55. A) B) Andy has a (toy) garage that is supposed to have four cars in it. According to Andy, X = the number of cars that are actually in the garage at any given time follows the following distribution: Value of X 4 3 2 1 0 Probability 0.90 0.05 0.03 0.02 0 According to this model, what is the average number of cars that are in the garage at any given time? 3 cars C) 3.92 cars 3.83 cars D) 4 cars Use the following to answer questions 56–5...
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