Problem #1: | (a) | From a stack of 3 dice, one is taken and rolled twice. If, unknown to the gambler, one of the dice is weighted and has a 1/8 chance of rolling a 6, what is the probability that the gambler rolls two 6's? | (b) | If the gambler has rolled two sixes, what is the probability that he has rolled the weighted die? | | |
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Problem #2: | Many students entering unversity take a math course, 1J03. In this course, 7% of the students fail, and leave the university. 26% of the students pass, but get a low mark, and move on to 1E03. 67% of the students pass, and get a high mark, and move on to 1KR3. In 1E03, 15% fail, and leave the university. In 1KR3, 17% fail, and depart. If a student tells his parents he failed mathematics and had to leave the university, what is the probability that he failed out of 1E03? | | |
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Problem #3: | A production manager counts the number of items produced in his factory in a given 40 hour week. He records the following data: # Produced Per Hour | Number of Occurrences | Relative Frequency | 51 52 53 54 55 56 | 3 7 6 19 11 4 | a b c d e f | The third column in the above table contains the frequencies for arelativefrequency distribution associated with this data. Find the values ofa,b,c,d,e, and f. | | |
| | Enter the values ofa,b,c,d,e,f in that order, separated by commmas. |
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Problem #4: | The random variableYhas the following probability distribution. k | Pr(Y=k) | 3 6 9 12 15 | 0.2 0.22 0.3 0.09 0.19 | The random variable (3 - (Y/3))2has a probability distribution of the following form. k | Pr((3 - (Y/3))2=k) | a b c | d e f | where the values ofa,b, andc, are inincreasingorder. | (a) | Find the values ofa,b, andc. | (b) | Find the values ofd,e, and f. | | |
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Problem #5: | 38% of all pets sold at a pet store are dogs. One day, 12 people arrive at the store and purchase pets. (Note: One pet is purchased per person.) | (a) | What is the probability that exactly 5 of them are dogs? | (b) | If the store has only 10 dogs, what is the probability that they have sufficient dogs for sale that day? | | |
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Problem #6: | A single die is rolled 5 times. What is the probability that a six is rolled exactly once, if it is known that at least one six is rolled? | | |
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Problem #7: | A die is rolled 30 times, and the value on top of the die recorded. This produces the following results: Value | # Occurences | 1 2 3 4 5 6 | 8 3 2 4 3 10 | | (a) | For this data, compute the mean value on the die in this experiment. | (b) | Now, compute the expected value for this experiment. | | |
| | Round your answer to2 decimals. |
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Problem #8: | A carnival operator is constructing a new game. In this game, the player will place a bet. Then a ball is selecteded from an urn containing balls of three colours: 1 green ball, 5 red balls and 5 white balls. If a red ball is drawn, the player wins 3$, if a green ball is drawn, the player wins 4$, and if a white ball is drawn the player wins nothing. What should the carnival operator set the bet at such that on average he makes $0.50 profit a game? (That is, so the player loses $0.50) | | |
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Problem #9: | Suppose we are given a probability distribution that has a mean if 10 and a standard deviation of 0.9. Use the Chebyshev inequality to find a lower bound estimate of the following probabilities: | (a) | The probability that the outcome will lie between 8 and 12 | (b) | The probability that the outcome lies between 4.5 to 15.5 | | |
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Problem #10: | What is the probability that a normal random variable has an outcome within 3 standard deviations of the mean? | | |
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Problem #11: | In her first year of university, Mary recieved the following grades: 7, 10, 12, 6, 11, 6 Similarly in his first year, Bob recieved the following grades: 11, 10, 7, 11, 6, 11 | (a) | Compute the population mean and variance for Mary's grades. | (b) | Compute the population mean and variance for Bob's grades. | | |
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Problem #12: | Suppose that Student A's marks throughout the term had a mean of 90 with variance 9, and that Student B's marks throughout the term had a mean of 70 with variance 36. Which of the below statements is true? | | |
| (A)Neither student had a higher average and neither student was more consistent. (B)Neither student had a higher average and Student A was more consistent. (C)Student A had a higher average but neither student was more consistent. (D)Student A had a lower average but neither student was more consistent. (E)Student A had a lower average and was more consistent. (F)Student A had a higher average and Student B was more consistent. (G)Neither student had a higher average and Student B was more consistent. (H)Student A had a higher average and was more consistent. (I)Student A had a lower average and Student B was more consistent. Problem #12: | |
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Problem #13: | For the standard normal distribution, determine the following probabilities: | | |
| | Give your answer to4 decimals. |
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Problem #14: | For a normal random variable, with = 19, and = 10, find the following probabilities. | | |
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Problem #15: | A very reliable baseball player is known to get a hit when at bat 41% of the time. He is expected to have 107 more times at bat before the end of the season, and he is 50 hits away from breaking a league hitting record. What is the probability of him breaking that record before the end of the season? | | |
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Problem #16: | A child, (and mathematical genius!) wishes to estimate the variability in the number of candies he can collect from houses during trick-or-treating. He randomly selects asampleof 20 houses, and records the number of candies he gets at each: # Candies | # Houses | 0 1 2 3 4 | 1 8 5 3 3 | Find the sample variance he calculates using this data. | | |