# Questions on Algebra: Probability and statistics answered by real tutors!

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 Algebra: Probability and statistics Solvers Lessons Answers archive Quiz In Depth

 Question 413415: The average life of a particular battery is determined to be 56.2 hours with a standard deviation of 4.3 hours ,assume battery life is normally distributed. Batteries in the lower 10% do not meet min life requirement for a battery. What is the minimum life for the battery Click here to see answer by lovegod1(1)

 Question 429457: a six sided die is rolled twice. let Y and Z be the value of the first and second rolls, and let X be the maximum of the two. Please help me find the Variance of X. Click here to see answer by robertb(4012)

 Question 429430: If X is a normal random variable with a mean of 4, and if the probability that X is less than 5.76 is .72, then what is the standard deviation of X? Click here to see answer by robertb(4012)

 Question 429428: If X is a normal random variable with standard deviation 3.50, and if the probability that X is more than 10.83 is .1271, then what is the mean of X? Please work out solution so I can see how the answer was achieved. If X is a normal random variable with a standard deviation 3.50, and if the probability that X is less than 8.83 is .648, then what is the mean of X? Click here to see answer by robertb(4012)

 Question 429465: How can you make a fair game (one with probability 1/2 of winning) from tossing an unfair coin? If a coin has probability p of heads (with p not necessarily 1/2), show that for two tosses the events HT and TH have the same probability. Therefore, toss the coin twice: If you get HT call the result a "win," if you get TH call the result a "lose," and if you get HH or TT ignore those tosses and toss it twice more, repeating the procedure until you get HT or TH. "Win" and "lose" are equally likely, so each has probability 1/2 of occurring first. Any help is great THXS Click here to see answer by edjones(7569)
 Question 429465: How can you make a fair game (one with probability 1/2 of winning) from tossing an unfair coin? If a coin has probability p of heads (with p not necessarily 1/2), show that for two tosses the events HT and TH have the same probability. Therefore, toss the coin twice: If you get HT call the result a "win," if you get TH call the result a "lose," and if you get HH or TT ignore those tosses and toss it twice more, repeating the procedure until you get HT or TH. "Win" and "lose" are equally likely, so each has probability 1/2 of occurring first. Any help is great THXS Click here to see answer by richard1234(5390)

 Question 429454: A costume store sells 20 costumes, you and 3 friends go to the store separately. What is the probability that at least 2 of you pick the same costume ? Click here to see answer by edjones(7569)

 Question 429423: Two cards are are drawn from a standard deck of 52 cards. once a card is drawn, it is not replaced. Find the probability that you draw a queen followed by a jack as your first two cards. Click here to see answer by edjones(7569)

 Question 429544: The 24 students in your class are dividing into 4 equal groups. Your teacher put an equal number of papers containing the nuumbers 1 through 4 in a bag. If you are the first to select a paper, what is the probability that you will be in group 3? Click here to see answer by stanbon(57962)

 Question 429479: If X is a normal random variable with a standard deviation 3.50, and if the probability that X is less than 8.83 is .648, then what is the mean of X? Click here to see answer by ewatrrr(10682)

 Question 429444: Vail Resorts pays part-time seasonal employees at ski resorts on an hourly basis. At a certain mountain, the hourly rates have a normal distribution with a standard deviation of \$4.00. If 30 percent of all part-time seasonal employees make more than \$14.00 an hour, what is the average hourly pay rate at this mountain? Click here to see answer by ewatrrr(10682)

 Question 429555: 11 women and 9 men are the contestant in a competition.If 3 winners are ramdomly selected.what is the probability that they are all men? Click here to see answer by ewatrrr(10682)

 Question 429563: A bag contains 1 red ball, between 3 and 5 blue balls, and between 5 and 9 green balls. If a ball is chosen from the bag at random, what is a reasonable probability of choosing the red ball? Click here to see answer by ewatrrr(10682)

 Question 429565: I need assistance with this homework: A test consists of 10 true-or-false questions. An answer is randomly chosen for each question. What is the probability of answering exactly 4 questions correctly? Answer in fraction. What is the probability of answering at least 2 questions correctly? Answer in fraction. Click here to see answer by ewatrrr(10682)

 Question 429572: Please show me how to do these difficult homework problems: A new drug can cause two unwanted side effects: drowsiness and headache. 6% of its users experienced drowsiness, 4% experienced headache, and 2% experienced both. If a user experienced headache, what is the probability that he also experienced drowsiness? What is the percentage of users who experienced neither side effect? Click here to see answer by stanbon(57962)

 Question 429569: Please assist me with my homework: Suppose E and F are two INDEPENDENT events. Pr(E) = 0.8 and Pr(E∩F) = 0.2. Find Pr(E U F). Let the sample space of an experiment be S = {a, b, c, d, e}. Suppose Pr({a, b, c}) = 0.45, Pr(c) = 0.1, and Pr({c, d)} = 0.35. Find Pr(e). Click here to see answer by stanbon(57962)

 Question 429566: The shell thickness of eggs is Normally distributed with a mean of 0.38mm and a standard deviation of 0.03mm. (iv) If two eggs were selected at random how likely is it that both would have a shell thickness of at least 0.41mm? Click here to see answer by stanbon(57962)

 Question 429588: Tom sleeps an average of 7.73 hours a day. In one non-leap year, how many hours does Tom sleep? Click here to see answer by ewatrrr(10682)

 Question 429619: there are 90 students , 60 play clarinet and 40 play the trombone, 10 only play the trombone. find the probability of a student playing the trombone or the clarinet. Click here to see answer by ewatrrr(10682)

 Question 429671: Use a standard normal table to find the z-score that corresponds to the 30th percentile. Click here to see answer by ewatrrr(10682)

 Question 429667: If a couple plans to have seven children, how many gender sequences are possible? Click here to see answer by Alan3354(31518)

 Question 429701: Based on past experiences, the probability that Mia will finish the marathon run is 0.75, that Linda will finish is 0.50, and that Marty will finish is 0.70. Find the probability of the following events. a.Mia will not finish the race. b.Mia and Linda will finish, but Marty will not. Click here to see answer by stanbon(57962)

 Question 429698: A card is drawn from a deck, and a game spinner with three equal regions labeled 1, 2, and 3 is spun. Let A be the event that the number on the card is 2. Let B be the event that the number on the spinner is a 2. a.Find the number of elements in the sample space. b.Find the number of elements in the set describing each event: A, B, A union B, A intersection B. And find the probability of each. Click here to see answer by stanbon(57962)

 Question 429764: Two questions are on a test. There are 4 multiple choice answers for each question, but only one is right for each question. What is the probability you will get both questions correct. 1. A,B,C,D (Only one can be right) 2. A,B,C,D (Only one can be right) Probability of getting both questions correct? Click here to see answer by edjones(7569)
 Question 429764: Two questions are on a test. There are 4 multiple choice answers for each question, but only one is right for each question. What is the probability you will get both questions correct. 1. A,B,C,D (Only one can be right) 2. A,B,C,D (Only one can be right) Probability of getting both questions correct? Click here to see answer by stanbon(57962)

 Question 429724: joey put 4 red marbles, 5 green marbles, and 2 yellow marbles in a bag. He took one marble out at random and then replaced it. How many times out of 100 draws could he expect to draw out a red marble? Click here to see answer by stanbon(57962)

 Question 429721: A card is drawn from a dack, and a game spinner with three equal regions labeled 1, 2 and 3 is spun. Let A be the event that the number on the card is a 2. Let B be the event that the number on the spinner is a 2. a.Find the number of elements in the sample space. b.Find the number of elements in each set describing each event: A, B, A union(U) B, A intersection(upside down U) B. Click here to see answer by stanbon(57962)

 Question 429823: Let X and Y both be discrete uniform random variables on {0, 1, 2, 3, 4}. Let Z = |X-Y|. Find the PMF of Z. Please Help... Click here to see answer by robertb(4012)

 Question 429845: Info: There are two little lotteries in town, each of which sells exactly 100 tickets. 1. If each lottery has only one winning ticket, and you buy one ticket to each of the two lotteries, what is the probability that you will have 'two' winning tickets? 2. If each lottery has two winning tickets, and you buy two tickets to the same lottery, what is the probability that you will have two winning tickets? Click here to see answer by sudhanshu_kmr(1152)

 Question 429930: A doctor is using a method of treatment that is thought to be 94% successful. What is the probability that there are five failures in 15 treatments (round to the nearest thousandth)? Click here to see answer by ewatrrr(10682)

 Question 356787: In order to control costs, a company wishes to study the amount of money its sales force spends entertaining clients. The following is a random sample of six entertainment expenses (dinner costs for four people) from expense reports submitted by members of the sales force. \$157, \$132, \$109, \$145, \$125, \$139 a) Calculate x/- (should be - over x), s/2 (s squared), and s for the expenses data. In addition, show that the two different formulas for calculating s/2 give the same result. b) Assuming that the distribution of entertainment expenses is approximately normally distributed, calculate estimates of tolerance intervals containing 68.26 percent, 95.44 percent, and 99.73 percent of all entertainment expenses by the sales force. c) If a member of the sales force submits an entertainment expense (dinner cost for four) of \$190, should this expense be considered unusually high (and possibly worthy of investigation by the company)? Explain your answer. d) Compute and interpret the z-score for each of the six entertainment expenses. Click here to see answer by variety(1)

 Question 429958: Which hypothesis (H0 or Ha) is the "hoped for" or "suspected" hypothesis. Why? Click here to see answer by stanbon(57962)

 Question 430106: If two cars were faced away from each other back to back, both cars travelled 8 miles forward then made a 90 degree left turn and traveled another 6 miles, how far apart would they be? Click here to see answer by haileytucki(390)

 Question 430113: one colored chip- red,blue, or green- is selected at random and a die is rolled. Click here to see answer by stanbon(57962)
 Question 430113: one colored chip- red,blue, or green- is selected at random and a die is rolled. Click here to see answer by haileytucki(390)

 Question 430161: Question:study of long distance phone calls made from the corporate office revealed the length of calls in minutes and follows a normal distribution. Mean is 4.2 minutes and standard deviation is 0.60 minutes. a) what fraction of the calls last between 4.2 and 5 minutes? b) what fraction of the calls last more than 5 minutes? c) what fraction of the calls last between 5 and 6 minutes? d) what fraction of the calls last between 4 and 6 minutes? For A I took Z=4.2-4.2/.6 and got 0 with a p score of 0.0000 and then Z=5-4.2/.6 and got 1.333 with a p score of 0.4082 So is the final answer the 0.4082 because both Zscore land on one side of the curve or do I need to take the .5000 for the other side and subtract the 0.4082? For B I took Z= 5-4.2/0.6 and got 1.333 with a p score of 0.4082 and then I .5000 minus 0.4082 and got 0.0918 and then took 1-0.0918 and got a final answer of 0.9082 For C I took the z score for 5 and got 1.333 with probability of 0.4082 and z score for 6 and got 3.0 and probability of 0.4987. My question on C is what do I do next with the 2 probabilities, they are both on the same side of the curve so do I add them, or do I subtract them, and do I subtract anything from 1? Any help is greatly appreciated, I am taking this class online in a different time zone, so getting help from the instructor is difficult. Thank you:) Click here to see answer by stanbon(57962)

 Question 430159: Using Spinner to Generate Numbers: (KEEP IN MIND-that the SPINNER has just 3 sides to it using the numbers 1, 2, 3) Suppose the spinner here is spun twice in succession to determine a two-digit number. Giving each of the following. (a) the sample space _______________ (b) the probability of an odd number ___________ (c) the probability of an number with repeated digits ____________ (d) the total number of a greater than 30 ___________ (e) the probability of a prime number ___________ -My concern about this is if I am understanding this and setting up the formula correctly in order to solve it. Therefore, should I write it as the (a)3/6 (1st spun 1 or 2 or 3, 2nd spun 1 or 2 or 3) (b) 2/6 (odd numbers 1,3) (c)? (d)? (e) 2/6 (prime numbers 2, 3) (I just not sure which way I am supposed to write this damn formula because this stuff always has confused the hell out of me so much, so please help me understand this best as possible and if I am doing this correctly or not at all too.) Click here to see answer by stanbon(57962)

 Question 430173: Ryan has the numbers 1–30 listed on individual index cards. If Ryan randomly selects 1 card, what is the probability that it will be a multiple of 3 or a multiple of 11? Click here to see answer by ewatrrr(10682)

 Question 430155: Probabilities in Coin Tossing: Three fair coins are tossed. (a) Write out the sample space. -My concern: I'm just wondering if it is supposed to be write as and counted as (coin 1)=HT, (coin 2)=HT, etc.=6ways OR each one should be as (coins 123)=TTT,(coins 123)=TTH, etc.=8way or 24ways(-not sure which it is meant to be because this stuff always has confused the hell out of me so much, so please help me understand this best as possible)? Determine the probability of each event. (b) P(no heads)= (c) P(exactly on head)= (d) P(exactly two heads)= (e) P(three heads)= Click here to see answer by ewatrrr(10682)

 Question 430156: Probabilities of Seed Germination: In a hybrid corn research project, 200 seeds were planted, and 170 of them germinated. Find the empirical probability that any particular seed of this type will germinate. -My concern about this is if I am understanding this and setting up the formula correctly in order to solve it. Therefore, should I write it as P(germinate)= 170/200 OR P(planted)= 200/170 or 170/200. (I just not sure which way I am supposed to write this damn formula because this stuff always has confused the hell out of me so much, so please help me understand this best as possible and if I am doing this correctly or not at all too.) Click here to see answer by ewatrrr(10682)

 Question 430188: Can I get confirmation of may answers and help with the one I cant seem to get? At a bank 84% of all loan applications are a pprovable. There are 15 applications up for review: A) What is the probabilty that all 15 applications are approved? 0.073 B) What is the probabilty that at least 1 application is denied? I cant get this one C) What is the probability that fewer than 10 are approved? 0.023 Thanks, Dave Click here to see answer by ewatrrr(10682)

 Question 430186: Can I get help with this problem please: In 7 rolls of 2 fair dice what is the probabilty of obtaining a sum of 11 exactly 3 times? Thanks, Kim Click here to see answer by ewatrrr(10682)

 Question 430243: assum that Z-scores are normally distrubuted with a mean of 0 and a standard deviation of 1. Find the z-score that corresponds with D4. Click here to see answer by stanbon(57962)

 Question 430241: Assume that Z-scores are normally distributed with a mean of 0 and a standard deviation of 1. - If P(z large or equal c) = 0.8944, find c! Click here to see answer by ewatrrr(10682)

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