Exam 2 - Pretest DS-23

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1 Exam 2 - Pretest DS-23 Chapter (4,5,6) Odds 10/3/2017 Ferbrache MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Solve the problem. 1) A single die is rolled one time. Find the probability of rolling an odd number or a number less than 5. 1) A) 5 6 B) 2 3 C) 1 2 D) 1 2) One card is selected from a deck of cards. Find the probability of selecting a red card or a queen. 2) A) B) C) D) ) A survey revealed that 50% of people are entertained by reading books, 33% are entertained by watching TV, and 17% are entertained by both books and TV. What is the probability that a person will be entertained by either books or TV? Express the answer as a percentage. A) 66% B) 17% C) 83% D) 100% 4) Of the coffee makers sold in an appliance store, 6.0% have either a faulty switch or a defective cord, 2.6% have a faulty switch, and 0.8% have both defects. What is the probability that a coffee maker will have a defective cord? Express the answer as a percentage. A) 6.8% B) 4.2% C) 6.0% D) 3.4% 5) A survey of senior citizens at a doctor's office shows that 45% take blood pressure-lowering medication, 48% take cholesterol-lowering medication, and 7% take both medications. What is the probability that a senior citizen takes either blood pressure-lowering or cholesterol-lowering medication? Express the answer as a percentage A) 0% B) 4% C) 100% D) 86% 6) Below is a table of data from a survey given to 1600 teenagers asking them to estimate what percentage of their classmates are using drugs. Find the probability that a randomly selected girl thinks that 50% or more of her classmates are using drugs. Round your answer to the nearest hundredth. None 1% - 24% 25% - 49% 50% - 74% 75% or more Boys Girls A).10 B).08 C).21 D).17 3) 4) 5) 6) 7) If a single fair die is rolled, find the probability of a 4 given that the number rolled is odd. 7) A) 1 2 B) 1 6 C) 0 D) 1 8) If two fair dice are rolled, find the probability of a sum of 6 given that the roll is a double. 8) A) 1 3 B) 1 5 C) 1 4 D) 1 6 1

2 9) The Vardon Exploration Company is getting ready to leave for South America to explore for oil. One piece of equipment requires 10 batteries that must operate for more than 2 hours. The batteries being used have a 15 percent chance of failing within 2 hours. The exploration leader plans to take 15 batteries. Assuming that the conditions of the binomial apply, the probability that the supply of batteries will contain enough good ones to operate the equipment is: A) B) C) D) ) If the number of defective items selected at random from a parts inventory is considered to follow a binomial distribution with n = 50 and p = 0.10, the expected number of defective parts is: A) more than 10 B) approximately 2.24 C) 0.5 D) 5 11) Assuming that potholes occur randomly along roads, the number of potholes per mile of road could best be described by the: A) binomial distribution. B) hypergeometric distribution. C) continuous distribution D) Poisson distribution. 12) The number of visible defects on a product container is thought to be Poisson distributed with a mean equal to 3.5. Based on this, the probability that 2 containers will contain a total of less than 2 defects is: A) B) C) D) ) A local paint store carries 4 brands of paint (W, X, Y, and Z). The store has 5 cans of W, 3 cans of X, 6 cans of Y, and 15 cans of Z, all in white. It is thought that customers have no preference for one of these brands over another. If this is the case, what is the probability that the next 5 customers will select 1 can of W, X, Y and 2 cans of brand Z? A) Over.30 B) About.23 C) 0.25 D) Approximately.08 14) Because of bad weather, the number of days next week that the captain of a charter fishing boat can leave port is uncertain. Let x = number of days that the boat is able to leave port per week. The following probability distribution for the variable, x, was determined based on historical data when the weather was poor: 9) 10) 11) 12) 13) 14) Based on the probability distribution, what is the expected number of days per week the captain can leave port? A) 2.8 B) 3.7 C) 1.7 D) 4.5 2

3 15) The roll of a pair of dice has the following probability distribution, where the random variable is the sum of the values produced by each die: 15) 2 1/36 3 2/36 4 3/36 5 4/36 6 5/36 7 6/36 8 5/36 9 4/ / / /36 Calculate the variance of x. A) B) C) D) ) Jennings Assembly in Hartford, Connecticut, uses a component supplied by a company in Brazil. The component is expensive to carry in inventory and consequently is not always available in stock when requested. Furthermore, shipping schedules are such that the lead time for transportation of the component is not a constant. Using historical records, the manufacturing firm has developed the following probability distribution for the product's lead time. The distribution is shown here, where the random variable is the number of days between the placement of the replenishment order and the receipt of the item. 16) What is the average lead time for the component? A) B) C) D) ) For a binomial distribution with a sample size equal to 10 and a probability of a success equal to 0.30, what is the probability that the sample will contain exactly three successes? Use the binomial formula to determine the probability. A) B) C) D) ) If a binomial distribution applies with a sample size of n = 20, find the probability of at least 7 successes if the probability of a success is A) B) C) D) ) 18) 3

4 19) It is assumed that the time failures for an electronic component are exponentially distributed with a mean of 50 hours between consecutive failures. What is the probability that a component will be functioning after 60 hours? A) About 0.49 B) Approximately 0.30 C) About 0.21 D) About ) A randomly selected value from a normal distribution is found to be 2.1 standard deviations above its mean. What is the probability that a randomly selected value from the distribution will be greater than 2.1 standard deviations above the mean? A) B) C) D) ) The transportation manager for the State of New Jersey has determined that the time between arrivals at a toll booth on the state's turnpike is exponentially distributed with = 4 cars per minute. Based on this information, what is the probability that the time between any two cars arriving will exceed 11 seconds? A) Approximately 1.0 B) About 0.75 C) Approximately 0.48 D) About ) 20) 21) 22) For a standardized normal distribution, calculate P(z < 1.5). 22) A) B) C) D) ) A random variable is normally distributed with a mean of 25 and a standard deviation of 5. If an observation is randomly selected from the distribution, determine two values of which the smallest has 25% of the values below it and the largest has 25% of the values above it. A) and B) and C) and D) and ) The manager of a computer help desk operation has collected enough data to conclude that the distribution of time per call is normally distributed with a mean equal to 8.21 minutes and a standard deviation of 2.14 minutes. Based on this, what is the probability that a call will last longer than 13 minutes? A) About B) About C) Approximately D) About ) Students who have completed a speed reading course have reading speeds that are normally distributed with a mean of 950 words per minute and a standard deviation equal to 220 words per minute. Based on this information, what is the probability of a student reading at more than 1400 words per minute after finishing the course? A) B) C) D) ) 24) 25) 4

5 Answer Key Testname: EXAM2(PRETEST VERSION1) 1) A 2) C 3) A 4) B 5) D 6) C 7) C 8) D 9) C 10) D 11) D 12) D 13) D 14) B 15) B 16) D 17) B 18) A 19) B 20) D 21) C 22) B 23) C 24) D 25) D 5

Determine whether the given events are disjoint. 1) Drawing a face card from a deck of cards and drawing a deuce A) Yes B) No

Assignment 8.-8.6 Name MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. Determine whether the given events are disjoint. 1) Drawing a face card from