Question 1
Question
41. A set of families has the following distribution on number of children: x1, x2
Determine , if it is known that M(x) = 2 D(x) =1.2 ?
Question 2
Question
42. The lifetime of a machine part has a continuous distribution on the interval (0, 30) with
probability density function Calculate the probability that the
lifetime of the machine part is less than 6.
Answer
-
30/53
-
1/2
-
31/35
-
13/28
-
1/17
Question 3
Question
43. The lifetime of a machine part has a continuous distribution on the interval (0, 11) with
probability density function Calculate the probability that the lifteime of the machine part is less than 5.
Answer
-
1/17
-
7/20
-
10/11
-
19/35
-
7/11
Question 4
Question
44. A random variable X is given by the density function of distribution:n Find the integral function of distribution of the random variable X?
Question 5
Question
45. A random variable X is given by the density function of distribution: Find the integral function of distribution of the random variable X?
Question 6
Question
47. A random variable X is given by the integral function of distribution:
Find the mathematical expectation of the random variable X?
Question 7
Question
49. A random variable X is given by the integral function of distribution:
If , then find the dispersion of the random variable X?
Question 8
Question
51. The lifetime in hours of a certain kind of radio tube is a random variable having a probability density function given by: What is the probability that exactly 1 of 5 such tubes in a radio set will have to be replaced within the first 150 hours
of operation?
Answer
-
80/243
-
40/243
-
0
-
160/243
-
1/3
Question 9
Question
52. The lifetime in hours of a certain kind of radio tube is a random variable having a probability density function given by: What is the probability that exactly 3 of 5 such tubes in a radio set will have to be replaced within the first 150 hours
of operation?
Answer
-
80/243
-
40/243
-
0
-
160/243
-
1/3
Question 10
Question
53. A random variable X is given by the integral function of distribution:
Find the probability that random variable takes the values on .
Answer
-
117/125
-
208/125
-
63/125
-
113/125
-
1/5
Question 11
Question
54. A random variable X is given by the density function of distribution:
Find the value of C?
Question 12
Question
56. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| > 3.
Question 13
Question
57. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| > 3.
Question 14
Question
58. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| > 3.
Question 15
Question
59. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| < 1.
Question 16
Question
60. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| > 1.
Question 17
Question
61. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| > 2.
Question 18
Question
62. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| > 3.
Question 19
Question
63. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| > 5.
Question 20
Question
64. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| > 4.
Question 21
Question
65. A discrete random variable X is given by the following law of distribution:
By using the Chebyshev inequality estimate
the probability that |X – M(X)| < 4.
Question 22
Question
66. The probability that a shooter will beat out 10 aces at one shot is equal to 0.1 and the
probability to beat out 9 aces is equal to 0.3. Choose the correctly calculated probabilities of the
events.
Answer
-
P(beat out more than 8 aces) = 0.5
-
P(beat out more than 10 aces) = 0.2
-
P(beat out 9 or less aces) = 0.9
-
P(beat out 9 or less aces) = 0.3
-
P(beat out 9 or more aces) = 0.3
Question 23
Question
69. Three students pass an exam. Let be the event «the exam will be passed on “excellent” by the
i-th student» (i = 1, 2, 3). Which of the following events correctly expressed by and
their negations?
Question 24
Question
71. A random variable X is given by the integral function of distribution:
What does this tell us about the random
variable X? More than one option may be correct.
Answer
-
M (X) = 10
-
D(X) = 1/2
-
P (10 < X < 15) = 1/2
-
P (X < 0) = 0
-
M (X) = 3/10
Question 25
Question
74. The probability that a shooter hit in a target at one shot is equal to 0.8. The shooter has made 3
shots. Choose the correctly calculated probabilities of the events.
Answer
-
P(at least 1 of 3 shots will strike the target)=0.384
-
P(at least 1 of 3 shots will strike the target)=0.992
-
P(at least 2 of 3 shots will not strike the target)=0.189
-
P(at least 2 of 3 shots will strike the target)=0.845
-
P(neither of 3 shots will strike the target)=0.8
Question 26
Question
78. The probability to receive high dividends under shares at the first enterprise – 0.2, on the
second – 0.35, on the third – 0.15. Choose the correctly calculated probabilities that a
shareholder having shares of all the enterprises will receive high dividends.
Answer
-
P(at least on two enterprises) = 0.1315
-
P(exactly on two enterprises) = 0.4214
-
P(only at one enterprise) = 0.7
-
P(at least on one enterprise) = 0.4265
-
P(exactly on three enterprises) = 0.105
Question 27
Question
79. The probability to receive high dividends under shares at the first enterprise – 0.2, on the
second – 0.2, on the third – 0.3. Choose the correctly calculated probabilities that a shareholder
having shares of all the enterprises will receive high dividends.
Answer
-
P(only at one enterprise)=0.416
-
P(only at one enterprise)=0.7
-
P(at least on one enterprise)=0.426
-
P(at least on two enterprises)=0.354
-
P(exactly on three enterprises)=0.105
Question 28
Question
80. The first brigade has 6 tractors, and the second – 9. One tractor demands repair in each
brigade. A tractor is chosen at random from each brigade. Choose the correctly calculated
probabilities of events.
Answer
-
P(both chosen tractors demands repair)=1/54
-
P(one of the chosen tractors demands repair)=0.5
-
P(both chosen tractors demands repair)=0
-
P(both chosen tractors demands repair)=1/27
-
P(both chosen tractors are serviceable)=13/15
Question 29
Question
81. The first brigade has 5 tractors, and the second – 8. One tractor demands repair in each
brigade. A tractor is chosen at random from each brigade. Choose the correctly calculated
probabilities of events.
Answer
-
P(one of the chosen tractors demands repair)=11/40
-
P(one of the chosen tractors demands repair)=7/40
-
P(both chosen tractors demands repair)=1/20
-
P(both chosen tractors demands repair)=1/2
-
P(both chosen tractors are serviceable)=1/3
Question 30
Question
82. All of the letters that spell STUDENT are put into a bag. Choose the correctly calculated
probabilities of events.
Answer
-
P(drawing a S, and then drawing a T)=1/21
-
P(drawing a T, and then drawing a D)=1/42
-
P(selecting a vowel, and then drawing a U)=1/42
-
P(selecting a vowel, and then drawing a K)=1/42
-
P(selecting a vowel, and then drawing a T)=3/42
Question 31
Question
83. All of the letters that spell MISSISSIPPI are put into a bag. Choose the correctly calculated
probabilities of events.
Answer
-
P(of selecting a vowel, and then after returning the letter also drawing a M)=4/121
-
P(of drawing an I, and then after returning the letter also drawing a M)=3/121
-
P(of selecting a vowel, and then after returning the letter also drawing an O)=4/121
-
P(of selecting a vowel, and then after returning the letter also drawing a P)=6/121
-
P(of drawing a M, and then after returning the letter also drawing a S)=1/121
Question 32
Question
84. The first brigade has tractors n , and the second m . One tractor demands repair in each
brigade. A tractor is chosen at random from each brigade. Choose the correctly calculated
probabilities of events.
Answer
-
n=3, m=5, P(both chosen tractors demands repair)=1/15
-
n=3, m=6, P(one of the chosen tractors demands repair)=7/12
-
n=2, m=5, P(both chosen tractors demands repair)=0.3
-
n=2, m=3, P(both chosen tractors demands repair)=1/3
-
n=5, m=2, P(both chosen tractors are serviceable)=0.2
Question 33
Question
85. A jar of marbles contains 4 blue marbles, 5 red marbles, 1 green marble, and 2 black marbles.
A marble is chosen at random from the jar. After returning it again, a second marble is chosen.
Choose the correctly calculated probabilities of events.
Answer
-
P(green, and then red)=5/144
-
P(black, and then black)=1/12
-
P(red, and then black)=7/72
-
P(green, and then blue)=1/72
-
P(blue, and then blue)=1/6
Question 34
Question
86. If each of the regions in each spinner is the same size.
Choose the correctly
calculated probabilities of spinning each spinner.
Answer
-
P(getting a red sweater)=1/12
-
P(getting a white sweatshirt)=1/6
-
P(getting a white sweater)=5/12
-
P(getting a blue sweatshirt)=7/12
-
P(getting a blue t-shirt)=1/6
Question 35
Question
88. Mary is playing a game in which she rolls one die and spins a spinner.
Choose the correctly
calculated probabilities of spinning each spinner.
Answer
-
P(get the 1 and green)=0
-
P(get the 7 and red)=1/18
-
P(get the 3 and green)=1/18
-
P(get the 2 and black)=1/4
-
P(get the 1 and white)=1
Question 36
Question
90. Find the Bernoulli formula.
Question 37
Question
92. A coming up a grain stored in a warehouse is equal to 50%. What is the probability that the
number of came up grains among 100 ones will make from up to pieces (a grain – зерно)?
Question 38
Question
93. The probability of striking a target by a shooter at one shot is equal to 3/4 . Find the probability P
that at 100 shots the target will be struck no less than a and no more b times.
Question 39
Question
94. The probability of striking a target by a shooter at one shot is equal to 1/4. Find the probability P
that at 100 shots the target will be struck no less than a and no more b times.
Question 40
Question
95. Find approximately the probability that an event will happen exactly from a to b times at 400
trials if in each trial the probability of its occurrence is equal to 0.2.
Question 41
Question
96. Find approximately the probability that an event will happen exactly from a to b times at 484
trials if in each trial the probability of its occurrence is equal to 0.5.
Question 42
Question
97. A factory has sent 2500 good-quality products. The probability that one product has been
damaged at a transportation is 1/5 . Find the probability P that at the transportation it will be
damaged from to products.