Question 465606: Tomorrow I have exam and I must solve this problem. Please, help me.
37. Marks on a Chemistry test follow a normal distribution with a mean of 65 and a standard deviation of 12. Approximately what percentage of the students have scores below 50?
38. Suppose the test scores of 600 students are normally distributed with a mean of 76 and standard deviation of 8. The number of students scoring between 70 and 82 is:
39. The distribution of weights in a large group is approximately normally distributed. The mean is 80 kg. and approximately 68% of the weights are between 70 and 90 kg. The standard deviation of the distribution of weights is equal to:
43. A continuous random variable X is uniformly distributed over the interval [10, 16]. The expected value of X is
45. How many different three-member teams can be formed from six students?
46. How many different 6-letter arrangements can be formed using the letters in the word ABSENT, if each letter is used only once?
47. If P(E) is the probability that an event will occur, which of the followings must be false?
48. A die is rolled. What is the probability that the number rolled is greater than 2 and even?
49. A pair of dice is rolled. A possible event is rolling a multiple of 5. What is the probability of the complement of this event?
55. A pair of dice is rolled. A possible event is rolling a multiple of 5. What is the probability of the complement of this event?
56. Your state issues license plates consisting of letters and numbers. There are 26 letters and the letters may be repeated. There are 10 digits and the digits may be repeated. How many possible license plates can be issued with two letters followed by three numbers?
58. A fair coin is thrown in the air four times. If the coin lands with the head up on the first three tosses, what is the probability that the coin will land with the head up on the fourth toss?
59. A movie theater sells 3 sizes of popcorn (small, medium, and large) with 3 choices of toppings (no butter, butter, extra butter). How many possible ways can a bag of popcorn be purchased?
63. Heights of college women have a distribution that can be approximated by a normal curve with a mean of 65 inches and a standard deviation equal to 3 inches. About what proportion of college women are between 65 and 67 inches tall?
64. The probability is p = 0.80 that a patient with a certain disease will be successfully treated with a new medical treatment. Suppose that the treatment is used on 40 patients. What is the "expected value" of the number of patients who are successfully treated?
65. A medical treatment has a success rate of 0.8. Two patients will be treated with this treatment. Assuming the results are independent for the two patients, what is the probability that neither one of them will be successfully cured?
66. A set of possible values that a random variable can assume and their associated probabilities of occurrence are referred to as ...
70. Two events each have probability 0.2 of occurring and are independent. The probability that neither occur is
71. A smoke-detector system consists of two parts A and B. If smoke occurs then the item A detects it with probability 0.95, the item B detects it with probability 0.98 whereas both of them detect it with probability 0.94. What is the probability that the smoke will not be detected?
73. A company which produces a particular drug has two factories, A and B. 30% of the drug are made in factory A, 70% in factory B. Suppose that 95% of the drugs produced by the factory A meet specifications while only 75% of the drugs produced by the factory B meet specifications. If I buy the drug, what is the probability that it meets specifications?
74. Twelve items are independently sampled from a production line. If the probability any given item is defective is 0.1, the probability of at most two defectives in the sample is closest to …
75. A student can solve 6 from a list of 10 problems. For an exam 8 questions are selected at random from the list. What is the probability that the student will solve exactly five problems?
76. Suppose that 10% of people are left handed. If 8 people are selected at random, what is the probability that exactly 2 of them are left handed?
77. Suppose a computer chip manufacturer rejects 15% of the chips produced because they fail presale testing. If you test 4 chips, what is the probability that not all of the chips fail?
Answer by stanbon(75887)   (Show Source):
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