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

Algebra ->  Algebra  -> Probability-and-statistics -> Questions on Algebra: Probability and statistics answered by real tutors!      Log On

 Ad: Algebrator™ solves your algebra problems and provides step-by-step explanations! Ad: Algebra Solved!™: algebra software solves algebra homework problems with step-by-step help!

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

 Question 141594: An auditor reviewed 25 oral surgery insurance claims from a particular surgical office, determining that the mean out-of-pocket patient biling above the reimbursed amount was \$275.66 with a standard deviation of \$78.11. (a) At the 5 percent level of significance, does this sample prove a violation of the guideline that the average patient should pay no more than \$250 out-of-pocket? State your hypothesis and decision rule. (b) Is this a close decision? Click here to see answer by stanbon(57290)

 Question 141565: one letter of the alphabet appears on each of 26 cards. you choose a card at random and then replace it. then you choose a secind card. assume Y is consonant. P(I,A) Click here to see answer by stanbon(57290)

 Question 141514: The management of White Industries is considering a new method of assembling its golf cart. The present method requires 42.3 minutes, on the average, to assemble a cart. The mean assembly time for a random sample of 24 carts, using the new method, was 40.6 minutes, and the standard deviation of the sample was 2.7 minutes. Using a 0.10 level of significance, setup a Hypothesis test. Can we conclude that the assembly time using the new method is faster? Click here to see answer by stanbon(57290)

 Question 141448: The probability is 1 in 4,000,000 that a single auto trip in the United States will result in a fatality. Over a lifetime, an average U.S. driver takes 50,000 trips. (a) What is the probability of a fatal accident over a lifetime? Explain your reasoning carefully. Hint: Assume independent events. Why might the assumption of independence be violated? (b) Why might a driver be tempted not to use a seat belt “just on this trip”? Click here to see answer by stanbon(57290)

 Question 141752: This problem is driving me nuts!! Please Assist :/ "Two cards are drawn from a standard deck of 52 cards. Find each Probability P(Both Kings or Both Black) P(Both Face Cards of Both Red) Click here to see answer by stanbon(57290)

 Question 141846: Does lovastatin (a cholesterol-lowering drug) reduce the risk of heart attack? In a Texas study, researchers gave lovastatin to 2,325 people and an inactive substitute to 2,081 people (average age 58). After 5 years, 57 of the lovastatin group had suffered a heart attack, compared with 97 for the inactive pill. (a) State the appropriate hypotheses. (b) Obtain a test statistic and p-value. Interpret the results at α = .01. (c) Is normality assured? (d) Is the difference large enough to be important? (e) What else would medical researchers need to know before prescribing this drug widely? (Data are from Science News 153 [May 30, 1998], p. 343.) Click here to see answer by stanbon(57290)

 Question 141845: An experimental medication is administered to 16 people who suffer from migraines. After an hour, 10 say they feel better. Is the medication effective (i.e., is the percent who feel better greater than 50 percent)? Use α = .10, explain fully, and show all steps. Click here to see answer by stanbon(57290)

 Question 141844: 9.65 A consumer agency tested 290 hams, finding that 64 were underweight. (a) Construct a 95 percent confidence interval for the true percent of underweight hams. (b) If the goal is to reduce the incidence of underweight hams to 25 percent or less, does this sample show that the goal is being achieved? (c) Explain how this confidence interval is equivalent to a two-tailed test at α = .05. (Data are from Detroit Free Press, March 9, 1999, p. 2A.) Click here to see answer by stanbon(57290)

 Question 141843: 9.63 In the Big Ten (the NCAA sports league) a sample showed that only 267 out of 584 freshmen football players graduated within 6 years. (a) At α = .05 does this sample contradict the claim that at least half graduate within 6 years? State your hypotheses and decision rule. (b) Calculate the p-value and interpret it. (c) Do you think the difference is important, as opposed to significant? Click here to see answer by stanbon(57290)

 Question 141967: 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. (Data are from a project by statistics students Kim Dyer, Amy Pease, and Lyndsey Smith.) Click here to see answer by stanbon(57290)

 Question 141966: 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(57290)

 Question 141965: In Dallas, some fire trucks were painted yellow (instead of red) to heighten their visibility. During a test period, the fleet of red fire trucks made 153,348 runs and had 20 accidents, while the fleet of yellow fire trucks made 135,035 runs and had 4 accidents. At α = .01, did the yellow fire trucks have a significantly lower accident rate? (a) State the hypotheses. (b) State the decision rule and sketch it. (c) Find the sample proportions and z test statistic. (d) Make a decision. (e) Find the p-value and interpret it. (f ) If statistically significant, do you think the difference is large enough to be important? If so, to whom, and why? (g) Is the normality assumption fulfilled? Explain. DATA Accident Rate for Dallas Fire Trucks Statistic Red Fire Trucks Yellow Fire Trucks Number of accidents x1 = 20 accidents x2 = 4 accidents Number of fire runs n1 = 153,348 runs n2 = 135,035 runs Click here to see answer by stanbon(57290)

 Question 141842: A coin was flipped 60 times and came up heads 38 times. (a) At the .10 level of significance, is the coin biased toward heads? Show your decision rule and calculations. (b) Calculate a p-value and interpret it. Click here to see answer by stanbon(57290)

 Question 141841: On eight Friday quizzes, Bob received scores of 80, 85, 95, 92, 89, 84, 90, 92. He tells Prof. Hardtack that he is really a 90+ performer but this sample just happened to fall below his true performance level. (a) State an appropriate pair of hypotheses. (b) State the formula for the test statistic and show your decision rule using the 1 percent level of significance. (c) Carry out the test. Show your work. (d) What assumptions are required? (e) Use Excel to find the p-value and interpret it. Click here to see answer by stanbon(57290)

 Question 142044: A fair coins is tossed 5 times. What is the probability of obtaining exactly 3 heads? I found a formula that looks like C(5,3)=5!/[3!(5-3)!] My problem is, I don't know if this formula is right, or how to solve it. I believe this is supposed to tell you the number of possible outcomes??? Click here to see answer by stanbon(57290)

 Question 142078: Please help this problem is giving me a headache. What is the probability of choosing a man and is wearing a hat. There are 20 men with hats, 30 men without hats, 25 woman with hats, and 10 woman without hats. Click here to see answer by stanbon(57290)

 Question 142058: This is the socond problem I am struggling with. Any help would be appericated. thank you. 7.55 Tire pressure in a certain car is a normally distributed random variable with mean 30 psi (pounds per square inch) and standard deviation 2 psi. The manufacturer’s recommended correct inflation range is 28 psi to 32 psi. A motorist’s tire is inspected at random. (a) What is the probability that the tire’s inflation is within the recommended range? (b) What is the probability that the tire is under-inflated? *(c) The Alliance of Automotive Manufacturers has developed a microchip that will warn when a tire is 25 percent below the recommended mean, to warn of dangerously low tire pressure. How often would such an alarm be triggered? (See The Wall Street Journal, July 14, 2004.) Click here to see answer by stanbon(57290)

 Question 142057: I need help understanding this problem. I am lost In the Ardmore Hotel, 20 percent of the customers pay by American Express credit card. (a) Of the next 10 customers, what is the probability that none pay by American Express? (b) At least two? (c) Fewer than three? (d) What is the expected number who pay by American Express? (e) Find the Standard deviation. Any help would be great. Thank you Click here to see answer by stanbon(57290)

 Question 142198: Please help with this problem. What is the probability of choosing a man that is wearing a hat. There are 20 men with hats, 30 men without hats, 25 women with hats, and 10 women without hats. Click here to see answer by stanbon(57290)

 Question 142256: Please help with this problem. You are given 12 to 1 odd against hitting a solid 17 on Roulette number. This means that you win \$12 if you succeed and you lose \$1 if you fail. Calculate the expected value for one roll. Click here to see answer by stanbon(57290)

 Question 142307: sonia cds are all mixed up in a box twelve cds are rock eight are jazz and five are classical if she reaches in and selects three at random find the probability. p (all jazz) Click here to see answer by stanbon(57290)

 Question 130205: Convert each of the following x intervals to standardized z intervals: a) 5 ≤ x ≤ 8 b) x ≥ 4 Convert each of the following z intervals to raw score x intervals: c) z ≥ -2 d) 0 ≤ z ≤ 2 e) z ≤ 3 Click here to see answer by stanbon(57290)

 Question 127278: In an election, it was estimated that person A would receive 200 of the 300 electoral votes. What was the standard error? This question is due on day 6. Click here to see answer by stanbon(57290)

 Question 142493: Hi please can you tell me if the probability value of 0.0133 is significant or not? Click here to see answer by stanbon(57290)

 Question 142504: A bag only has blue and green chips. The probability of drawing a blue chip is 5/12. Find P(green). Thanks agian!!!! Click here to see answer by solver91311(16877)

 Question 142503: A ranch has 132 cows. You pick 32 of them at random and find that 18 of those cows have spots. Predict the numbe of cows on the ranch that have spots. Thanks so much!!!!! Click here to see answer by solver91311(16877)

 Question 142508: Suppose you roll a number cube twice. What is the pobability of getting a 2 on the first roll and a 5 on the second roll? Thanks yall agian. Click here to see answer by rapaljer(4667)

 Question 142502: Pam and Tony play a game 18 times. Tony wins 8 times and Pam wins 10 times. A.) Find the experimental probability that Pam wins. B.) Find the expeimental probability that Tony wins. C.) If Pama and Tony play the game 18 more times, must the experimental pobabilites remain the same? Explain please Thank you 1000 million times!!!! Click here to see answer by solver91311(16877)

 Question 142507: Determine if the events ae independent. Explain you answers. A.) You roll two number cubes. One shows a 3 Th other shows a 1. B.) You draw a ed marble fom hte bag containg red and yellow marbles. You do no put the marble back. you draw another red marble. Click here to see answer by rapaljer(4667)

 Question 142506: A bag contains four red,four blue, and thee green cubes. Cubes are drawn twice with replacement. Find each probability. 1.) P(both red) Thank yall Click here to see answer by rapaljer(4667)

 Question 142501: Suppose you read in the newspaper that the probability of rain is 10%. Write this probability as a fraction and as a decimal. Thanks so much Click here to see answer by rapaljer(4667)

 Question 142505: Use the counting principle to find the number of permutaions of the letters in GLACIER. Thank yall Click here to see answer by rapaljer(4667)

 Question 142426: describe the combined variation that is modeled by each formula. V=lwh Click here to see answer by stanbon(57290)

 Question 142549: Exercise using Excel The School Committee members of a midsized New England city agreed that a strict discipline code has caused an increase in the number of student suspensions. The number of suspensions for September 1992 - February 1993 for a sample of the schools is provided below. {Data} The average number of suspensions for the previous year mean{X bar} = 130.5 and the Standard deviation {STDEV} was 158.2 (a) Set up the null and alternative hypothesis to test if the averave number of suspensions has changed. (b) Test your hypothesis with alpha = 0.05. (c) Find the p value. (d) Display the data in an Excel Chart to see if it is reasonable to assume that the underlaying population distribution is normal. (e) Based on the p value, what can you conclude about the average number of suspensions? Data: Suspensions Central 245 a) - c) mu = 195 MCDI 1 Step 1 H(0) mean equal 130.5 Chestnut 65 H(A) mean not equal 130.5 Duggan 133 Sigma is given as = 158.2 Kennedy 97 Step 2 Critical Values (Z) = +/-1.96 because alpha is 0.05 Forest Park 149 (n)^0.5 Z P(Z<-1.352) p = 2*P(Z<-1.352) = 2*0.0885 Putnam 1024 Step 3 Test Statistic Z 3.317 Calculate Z here in cell H25. Kiley 56 p value = 0.177 Central Academy 254 Why is Z minus? Commerce 114 Step 4/5 d) See Below. Bridge 7 e) What do you think? STDEV= 287.15 mu = 195.00 ReOrder MCDI 1 Bridge 7 Kiley 56 Chestnut 65 Kennedy 97 Commerce 114 Duggan 133 Forest Park 149 Central 245 Central Academy 254 Putnam 1024 Click here to see answer by stanbon(57290)

 Question 142565: Find a confidence interval for μ assuming that each sample is from a normal population. a. ¯x = 14, σ = 4, n = 5, 90 percent confidence b. ¯x = 37, σ = 5, n = 15, 99 percent confidence c. ¯x = 121, σ = 15, n = 25, 95 percent confidence Click here to see answer by stanbon(57290)

 Question 142566: Calculate the test statistic and p-value for each sample. a. H0: μ = 60 versus H1: μ = 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(57290)