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20 Spring Semester "Probability Theory X" 1 online usually work
papers Total: 100 Score: 100
First, multiple choice (a total of 25 questions, a total of 75 points)
1. The bag has five white balls and three black balls, which take any two balls, then the probability of obtaining two balls of the same color is
A.0.4624
B.0.8843
C.0.4688
D.0.4623
2. set A, B, C three random events, which of the following means "at least one happen"?
A.ABC
BA∪B∪C
C. (A∪B) ∩C
D.AB∪C
3. The set X, Y is the joint distribution function F (x, y), then F (+ ∞, y) equal to:
A.0;
B.1;
distribution function of CY;
density function of DY.
4. set a car on the road bound for a destination to go through four lights each with probability 1/2 lights to allow or banning cars. X represents the first time in a car stopped, it is the probability of two lights by:
A.0.25
B.0.125
C.0.0625
D.1
The set X ~ (2,9), and P (X> C) = P (X <C), is = C ()
A.1
B.2
C.3
D.4
6. Event A, B satisfy if P (A) + P (B )> 1, then A and B must
A. opposing
B. incompatible
C. mutually independently
D. not mutually exclusive
7. For any two random variables X and Y, if E (XY) = E (X ) E (Y) is
the AD (the XY) = D (X) D (the Y)
the BD (the Y + X) = D (X ) + D (Y)
the CX and Y are independently
DX and Y are independently
It is a joint distribution function of the nature of a 8.X and Y:
the probability of A. and events;
probability B. post events;
probability C. poor events;
probability D. opposition events.
9. The set X, Y is the joint density function p (x, y), put p (x, y) on the x Points obtained:
A.0;
B.1;
distribution function of CY;
density function of DY.
10. From a total of 100 to 100 positive integers, either take a number, known a number taken no more than 50, seeking is the probability that a multiple of 2:
A.0.3
B.0.4
C.0.5
D.0.6
11. With regard to the independence, the following statement is wrong is
A. If A1, A2, A3, ......, An independent, then any number of events which are still independent
B. If A1, A2, A3, ......, An mutual after independence, then any number of events in which the opposite event them into independent still
C. If a and B are independent, B and C independently of one another, C and a are independent, then a, B, C each independently
D If A, B, C independently of each other, then A + B and C each independently
12.A, B probability two events are greater than zero, and A, B opposition, then the following is not true for the
AA, B incompatible
BA, B independent
CA, B is not independent
DA, B compatibility
13. Center Standardization do a random variable, it refers to the aspiration becomes variance becomes
A.0,1
B.1,0
C.0,0
D.1,1
14. The box is equipped with four probability black balls 6 white balls, without taking back the ball 3, only one ball is taken to the black:
A.0.5;
B.0.3;
C.54 / 125;
D .36 / 125.
15 is provided in the box 10 wooden balls, six glass balls, glass balls has two red, four blue; three wooden balls have red, blue 7, is taken from any of the cassette a ball, is represented by a "to get blue ball"; B represents "take a glass ball." Is P (B | A) =
A.3 /. 5
B.4 /. 7
C.3 /. 8
D.4 /. 11
16. A correlation coefficient of random variable X is 0.9 and Y, when Z = X-0.4, Y is Z is a correlation coefficient
A.0.1
B. 0.1-
C.0.9
D. 0.9-
17. optional in some schools in which a student, set up event A: selected students are boys "; B is selected students third grade students." Then P (A | B) is the meaning of:
A. selected students is the probability that the third grade boys
B. known third-year students are selected, he is the probability boys
C. selected students are known boy, a third-year student of probability
D. selected third grade students is the probability that he or boys
18. A and B is provided for the two independent events, P (B)> 0, then P (A | B) =
the AP (A)
on BP (B)
C.1-P (A)
the DP (AB)
19. A set, B for the two chess game, consider the event A = {} Jiashengpan B negative, the opposite event A is
A. {A minus B wins}
B. {AB} draw
C. A negative} {
D {A} negative draw or
20. A random variable X normal distribution N (0,1), belonging to a given (0,1), the number ua satisfy P {X> ua} = a , if P {| X | <x} = a, then x is equal to ()
A.ua/2
B.u1-A / 2
a Cu (. 1-A) / 2
D.u1-A
21. The set P (A) = 0.8, P (B) = 0.7, P (A|B) = 0.8, the following conclusions are correct
AA and B independently
BA and B are mutually exclusive
C. {FIG}
the DP (A + B) = P + P
22. The uniform quality of a coin thrown 100 consecutive times, X represents the number of positive appear, then X obedience ().
The AP (1/2)
BB (100,1 / 2)
the CN (. 1 / 2,100)
DB (50, 1/2)
23. There are 5 pots tennis, three new, the old 2, each taking a ball, there is a continuous back extracted twice, the note A to the "first to take the new ball" This event; B to remember "to take the second new ball" incident. In a known probability of the first or second ball taken into the new condition, the first time a new ball is taken:
the AP (B | A)
on BP (A | A∪B)
the CP (B | A ∪ B)
the DP (A | B)
24. If X and Y, independently, and X and Y are normally distributed, then X + Y obey
A. uniform distribution
B. binomial
C. normal
D. Poisson distribution
25. If the probability of two simultaneous events A and B is P (AB) = 0, then
AA and B is incompatible (repulsion)
BA, B is unlikely event
CA, B may not be impossible event
DP (A) = 0 or P (B) = 0
Second, determine the questions (5 questions total of 25 points)
is small sample size 26. The binomial distribution can be approximated by a normal distribution.
27. small probability event refers to the unlikely event occurred.
28. The utilization conditions to be met possibility to calculate the probability that the number of all possible results of the experiment are known, and as the likelihood of each experimental outcome.
29. In any case, can be used such as the possibility to calculate the probability.
30. A, B follows the two games: a card number from 1 to 20 in an arbitrary extracted, if the drawn figure is a multiple of 3, then A wins; if the drawn numbers are multiples of 5, B is the winner, this time for this game and B sides is fair.
