(내공드릴께요ㅠ)다른 사람들은 그렇게 어렵지 않은 확률 문제라고 하는데...
-
게시물 수정 , 삭제는 로그인 필요
과제인데, 제가 영어도 수학도 잘 못해서 ^^;
모쪼록 한 문제라도 아시는 분들은 도움을 주셨으면 고맙겠습니다ㅠ
-------------------------------------
1. A box contains 4 bad and 6 good tubes. Two are drawn out together. One of them is tested and found to be good. What is the probability that the other one is also good?
2. In a bolt factory, machines A, B, and C manufacture 25, 35, and 40 percent of the total output, respectively. Of their outputs, 5, 4, and 2 percent, respectively, are defective bolts. A bolt is chosen at random and found to be defective. What is the probability that the bolt came from machine A? B? C?
3. Each of two persons tosses three fair coins. What is the probability that they obtain the same number of heads?
4. Suppose that twice as many items are produced (per day) by machine 1 as by machine 2. However, about 4 percent of the items from machine 1 tend to be defective while machine 2 produces only about 2 percent defectives. Suppose that the daily output of the two machines is combined. A random sample of 10 is taken from the combined output. What is the probability that this sample contains 2 defectives?
5. A point is chosen at random on a line of length L. What is the probability that the ratio of the shorter to the longer segment is less than 1/4?
6. Suppose that the life length (in hours) of a certain radio tube is a continuous random variable X with pdf f(x) = 100/x2, x>100, and elsewhere.
(a) What is the probability that a tube will last less than 200 hours if it is known that the tube is still functiong after 150 hours of service?
(b) What is the probability that if 3 such tubes are installed in a set, exactly one will have to be replaced after 150 hours of service?
(c) What is the maximum number of tubes that may be inserted into a set so that there is a probability of 0.5 that after 150 hours of service all of them are still functioning?
7. Suppose that the discrete random variable X assumes the values 1,2, and 3 with equal probability. Find the probability distribution of Y =2X＋3
과제인데, 제가 영어도 수학도 잘 못해서 ^^;
모쪼록 한 문제라도 아시는 분들은 도움을 주셨으면 고맙겠습니다ㅠ
-------------------------------------
1. A box contains 4 bad and 6 good tubes. Two are drawn out together. One of them is tested and found to be good. What is the probability that the other one is also good?
2. In a bolt factory, machines A, B, and C manufacture 25, 35, and 40 percent of the total output, respectively. Of their outputs, 5, 4, and 2 percent, respectively, are defective bolts. A bolt is chosen at random and found to be defective. What is the probability that the bolt came from machine A? B? C?
3. Each of two persons tosses three fair coins. What is the probability that they obtain the same number of heads?
4. Suppose that twice as many items are produced (per day) by machine 1 as by machine 2. However, about 4 percent of the items from machine 1 tend to be defective while machine 2 produces only about 2 percent defectives. Suppose that the daily output of the two machines is combined. A random sample of 10 is taken from the combined output. What is the probability that this sample contains 2 defectives?
5. A point is chosen at random on a line of length L. What is the probability that the ratio of the shorter to the longer segment is less than 1/4?
6. Suppose that the life length (in hours) of a certain radio tube is a continuous random variable X with pdf f(x) = 100/x2, x>100, and elsewhere.
(a) What is the probability that a tube will last less than 200 hours if it is known that the tube is still functiong after 150 hours of service?
(b) What is the probability that if 3 such tubes are installed in a set, exactly one will have to be replaced after 150 hours of service?
(c) What is the maximum number of tubes that may be inserted into a set so that there is a probability of 0.5 that after 150 hours of service all of them are still functioning?
7. Suppose that the discrete random variable X assumes the values 1,2, and 3 with equal probability. Find the probability distribution of Y =2X＋3
