# 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 271411: 9.19 Calculate the test statistic and p-value for each sample. a. H0: μ = 60 versus H1: μ /=(not = to) 60, α = .025, ¯ x = 63, σ = 8, n = 16 b. H0: μ ≥ 60 versus H1: μ < 60, α = .05, ¯ x = 58, σ = 5, n = 25 c. H0: μ ≤ 60 versus H1: μ > 60, α = .05, ¯ x = 65, σ = 8, n = 36 Click here to see answer by stanbon(57282)

 Question 271410: 9.10 In a recent survey, 10 percent of the participants rated Pepsi as being “concerned with my health.” PepsiCo’s response included a new “Smart Spot” symbol on its products that meet certain nutrition criteria, to help consumers who seek more healthful eating options. At α = .05, would a follow-up survey showing that 18 of 100 persons now rate Pepsi as being “concerned with my ealth” prove that the percentage has increased? Click here to see answer by stanbon(57282)

 Question 271500: In bag there are 3 green marbles, 2 red marbles, 2 blue marbles, and 5 yellow marbles. What is the probability that Tyrell picks a green marble puts it back, back the picks a yellow marble. The probablility of a green marble is 1/4, and the probability of the yellow marble is 5/12? Click here to see answer by edjones(7569)

 Question 271399: What is the probability of getting nine numbers that are all nines? Click here to see answer by stanbon(57282)

 Question 271391: 10.56 A sample of 25 concession stand purchases at the October 22 matinee of Bride of Chucky showed a mean purchase of \$5.29 with a standard deviation of \$3.02. For the October 26 evening showing of the same movie, for a sample of 25 purchases the mean was \$5.12 with a standard deviation of \$2.14. The means appear to be very close, but not the variances. At α = .05, is there a difference in variances? Show all steps clearly, including an illustration of the decision rule. Click here to see answer by stanbon(57282)

 Question 271300: 10.46 To test the hypothesis that students who finish an exam first get better grades, Professor Hardtack kept track of the order in which papers were handed in. The first 25 papers showed a mean score of 77.1 with a standard deviation of 19.6, while the last 24 papers handed in showed a mean score of 69.3 with a standard deviation of 24.9. Is this a significant difference at α = .05? (a) State the hypotheses for a right-tailed test. (b) Obtain a test statistic and p-value assuming equal variances. Interpret these results. (c) Is the difference in mean scores large enough to be important? (d) Is it reasonable to assume equal variances? (e) Carry out a formal test for equal variances at α = .05, showing all steps clearly. Click here to see answer by stanbon(57282)

 Question 271586: you have 1 of 1000 tickets in a raffle. what is the probability that your ticket will be drawn as the winner Click here to see answer by edjones(7569)

 Question 271587: order these events from most probable to the least probable. a) the first baby born next year is a girl. b) the sun will set today c) you will live to be 100 years old. d)a classmate will live to 90 years e)a class mate will live to 90 years Click here to see answer by stanbon(57282)

 Question 271649: 1. Find the truncation error in the result of the following function for x=1/5 when we use i) first three terms ii) first four terms iii) first five terms Click here to see answer by Edwin McCravy(8893)

 Question 271651: 5. From a bag containing 2 rupee-coins and 3 twenty paise coins, a person is asked to draw two coins at random. Find the values of his expectation. Click here to see answer by Edwin McCravy(8893)

 Question 271650: 3. By using the Newton-Raphson’s method find the positive root of the quadratic equation 5x2 + 11x – 17 = 0 correct to 3 significant figures. Click here to see answer by Edwin McCravy(8893)

 Question 271204: To test the null hypothesis that the average lifetime for a particular brand of bulb is 750 hours versus the alternative that the average lifetime is different from 750 hours, a sample of 75 bulbs is used. If the standard deviation is 50 hours and a is equal to 0.01, what values for will result in rejection of the null hypothesis. Remember to determine whether this is a one- or two-tailed test. (Hint: This is similar to problem #4 but it is NOT a one-tailed test!) Click here to see answer by stanbon(57282)

 Question 271712: determine the probability of randomly guessing 40 questions correct out of 60 questions on a multiple choice test with possible selections a,b,c,d,e; by guessing Click here to see answer by solver91311(16872)

 Question 271747: calculate the probability of k successes for a binomial experiment consisting of n trials with the probability p of success on each trial. k>10, n=15, p=.4 Click here to see answer by edjones(7569)

 Question 271656: A certain disease occurs in 1 out of every 150 Americans. A test used to diagnose the disease has a false positive rate of 3% and a false negative rate of 6%. Find the probability that a person has the disease, given that they test positive, and the probability that a person does not have the disease, given that they test negetive. Click here to see answer by edjones(7569)

 Question 271761: Suppose that when a production process malfunctions, 50 out of 100 items are defective. In order to identify when the process is malfunctioning, how many items should be tested so that the probability that one or more items are found defective is at least 99%? Click here to see answer by Theo(3458)

 Question 271654: a) Out of every 100 jobs received at a computer center, 50 are of class 1, 30 of class 2 and 20 of class 3. A sample of 30 jobs is taken with replacement. i) Find the probability that the sample will contain ten jobs of each class. ii) Find the probability that there will be exactly twelve jobs of class 2. Click here to see answer by edjones(7569)

 Question 271787: A quiz cosists of 20 multiple-choice questions, each with 4 possible answers. For someone who makes random guesses for all of the answers, find the probability of passing if the minimum passing grade is 70 % Click here to see answer by stanbon(57282)

 Question 271871: Use the normal distribution to approximate the desired probability. International Airlines reports that 74% of its planes are on time. A check of 60 randomly selected planes shows that 38 of them arrived on time. Find the probability that among the 60 planes, 38 or fewer arrive on time. Click here to see answer by stanbon(57282)

 Question 271888: 1.A company recruits personnel for its sales department on the basis of special tests designed to judge the potential of the candidates. The following table gives test scores and the mean daily sales for 9 executives. Click here to see answer by stanbon(57282)

 Question 271891: The results of the last test in Algebra 2/Trig. class were normally distributed and had an average of 75. If the variance (σ2) was 25, what percent of the students taking the exam scored above an 80? What are the step to solving a question like this using a TI-83 Plus graphing calculator? What exactly do you enter in the calculator? Click here to see answer by stanbon(57282)

 Question 271896: If is a binomial random variable, compute for each of the following cases: (a) P(x => 1), n=4, p=0.4 P(x)= Click here to see answer by stanbon(57282)

 Question 271898: The results of the last test in Algebra 2/Trig. class were normally distributed and had an average of 75. If the variance (σ2) was 25, what percent of the students taking the exam scored above an 80? What are the step to solving a question like this using a TI-83 Plus graphing calculator? What exactly do you enter in the calculator? Click here to see answer by stanbon(57282)

 Question 271895: If is a binomial random variable, compute for each of the following cases: (a) P(x>1), n=9, p=0.1 P(x)= Click here to see answer by stanbon(57282)

 Question 271767: Given a normal distribution with a mean of 100 and a standard deviation of 10 what is the probability that a) x>75 b)x<70 c)x>80 or x>110 d) 80% of the data are between what two values(symmetrically distributed around the mean) Click here to see answer by stanbon(57282)

 Question 272042: how many possible outcomes are there from tossing 2 number cubes labled 1 through 6 Click here to see answer by stanbon(57282)
 Question 272042: how many possible outcomes are there from tossing 2 number cubes labled 1 through 6 Click here to see answer by Alan3354(30993)

 Question 272088: Historically, the publisher of Golf Illustrated has found that 62% of its subscribers renew their subscriptions. Because of the advent of the Internet and cable television, the publisher is concerned that the proportion of subscribers who renew their subscriptions may be declining. The publisher selects a random sample of 200 subscribers and finds that 104 plan to renew their subscriptions. Use (a=0.025). p = the population of subscribers to Golf Illustrated who renew. Calculate the p-value. Click here to see answer by stanbon(57282)

 Question 272098: In a family of three children there are 8 possibilities for the boy-girl combinations, such as BBG, GBG and so on. a) The probability of all boys equals the probability of all girls. What would each of these be? b) The probibility of 2 boys and 1 girl is equal to 3/8. Explain why it is 3/8 not 1/8. c) For this family of three children, what other situation would have a probability equal to 3/8? d) If the family had four children, how would the answer to part (a) change? Click here to see answer by stanbon(57282)

 Question 272155: You flip a fair coin 10 times. What is the probability that it lands on heads exactly 7 times? What is the probability that it lands on heads at least 7 times? Click here to see answer by stanbon(57282)

 Question 272174: A spinner was spun 40 times. The results are shown in the table below. Spinner Results Yellow 11 White 8 Red 6 Blue 6 Green 5 Orange 4 Which color's experimental probability matches its theoretical probability? Click here to see answer by stanbon(57282)

 Question 272158: Suppose a number is chosen at random from the set {0,1,2,3,...,170}. What is the probability that the number is a perfect cube? Click here to see answer by oberobic(2304)

 Question 272184: Solve the equation: (n+6)!/(n+4)!=12 Here is what I have done so far: (n+6)!/(n+4)!=12 (cross multiply) (n+6)!/(n+6)!=12/1 0= 12(n+4)!(n+5)!(n+6)!/ (n+6)! (The (n+6)!'s cancel out with each other) 0= (n+4) (n+5) (this is the result when you divide 12 by both sides) I don't know where to go from here. Did I make an error? or does n= -4 and n=-5 ? Click here to see answer by scott8148(6628)

 Question 272137: A man claims to have extrasensory perception. As a test, a fair coin is 25 flipped times, and the man is asked to predict the outcome in advance. He gets 22 out of 25 correct. What is the probability that he would have done at least this well if he had no ESP? Click here to see answer by edjones(7569)

 Question 272206: You plan to estimate the mean incubation period (in days) for sea birds. How many incubation periods of sea birds must you sample if you want to be 95% confident that the sample mean is within 3 days of the true population mean? You can assume that the standard deviation of incubation periods is 6 days? Click here to see answer by stanbon(57282)

 Question 272169: The rates of on-time flights for commercial jets are continuously tracked by the U.S. Department of Transportation. Recently, Southwest Air had the best reate with 80 % of its flights arriving on time. A test is conducted by randomly selecting 20 Southwest flights and observing whether they arrive on time. (a) Find the probability that at least 18 flights arrive on time. Click here to see answer by stanbon(57282)

 Question 272306: 1. Find the critical value zc necessary to form a confidence interval at 97% level of confidence Click here to see answer by Edwin McCravy(8893)

 Question 272413: this is the question im tying to figure out - Historically, 5 percent of a mail-order firm’s repeat charge-account customers have an incorrect current address in the firm’s computer database. (a) What is the probability that none of the next 12 repeat customers who call will have an incorrect address? (b) One customer? (c) Two customers? (d) Fewer than three? (e) Construct the probability distribution (using Excel or Appendix A), make a graph of its PDF, and describe its shape. Click here to see answer by stanbon(57282)

 Question 272486: Paul takes a 20 question true false test and randomly guesses at each answer what is the probability of his passing the quiz if it takes at least 12 correct answers Click here to see answer by stanbon(57282)

 Question 272487: I'm unsure about this question. I'm thinking its Convenience, but maybe stratified. Any help would be appreciated. A state representative selects four counties, and visits 11 cities in each. Random Systematic Cluster Stratified Convenience Click here to see answer by stanbon(57282)

 Question 272557: A baseball player has a batting average of 0.300. Over the season, he had 270 at-bats. What is the expected number of hits? Click here to see answer by stanbon(57282)

 Question 272597: A flashlight has 6 batteries, 2 of which are defective. If 2 are selected at random without replacement, find the probability that both are defective. Click here to see answer by Alan3354(30993)

 Question 272594: The expected value of the sampling distribution of the sample mean equals the populations mean A. When the population is symmetric. B. When the population size N>30. C. When the population is normally distributed. D. For all populations. Click here to see answer by stanbon(57282)

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