# 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 262382: Suppose a couple has six grandchildren. Determine the probability that all six grandchildren are girls. Explain in writing how you found your solution. I think I'm supposed to multiply 6 x 5 x 4 x 3 x 2 which = 720 possible outcomes for if the genders of their 6 grandchildren. Having all girls is 1 possibility out of 720. -> 1/720 = .14%. That just cannot be right. There cannot be that many options and the odds of having all girls cannot be less than 1%. I think I'm doing something wrong. Please help! Thanks!!! Click here to see answer by drk(1908)

 Question 262359: The Web-based company Oh Baby! Gifts has a goal of processing 95 percent of its orders on the same day they are received. If the 485 out of the next 500 orders are processed on the same day, would this prove that they are exceeding their goal, using α = .025? Click here to see answer by stanbon(60771)

 Question 262502: In a certain town, 5% of people commute to work by bicycle. If a person is selected randomly from the town, what are the odds against selecting someone who commutes by bicycle? Click here to see answer by richwmiller(10272)

 Question 262354: 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(60771)

 Question 262597: ok so there are 10 questions on a test which is a true or false test. what is the probability that a student can score at least a 70% on the test by just randomly guessing all answers. what if it was a multiple choice test with four choices per question, how does that probability channge Click here to see answer by stanbon(60771)

 Question 262590: x^2-8x+11=0 Solve the equation by completing the square. Click here to see answer by edjones(7794)

 Question 262665: What is the probability of dying on the day of your birth, 68 years later? Click here to see answer by richwmiller(10272)

 Question 262677: A standard six-sided die with its faces numbered 1 to 6 is rolled once, and a dime is tossed once. What is the probability of rolling a number less than 3 and tossing a tail? Express your answer as a common fraction. Click here to see answer by stanbon(60771)

 Question 262753: How many license plates are possible if they consist of three letters followed by three digits? Repetition is permitted. Click here to see answer by Alan3354(34673)

 Question 262812: Just want to check and see if I did this right? The Gallup Poll reported that 52% of Americans used a seat belt the last time they got into a car. If four people are selected at random, find the probability that they all used a seat belt the last time they got into a car. 0.52*0.52*0.52*0.52=7.3 people used the seat belt the last time they got in the car. Did I do this right? Click here to see answer by rfer(13569)

 Question 262826: I don't even know how to set up this problem. I am not finding examples, can you help please? Events A and B are mutually exclusive events defined on a common sample space. If P (A) = 0.3 and P(A or B) = 0.75, find P(B). (B) Events A and B are defined on a common sample space. If P(A) = 0.30, P(B) = 0.50, and P(A or B) = 0.72, find P(A and B) Click here to see answer by drk(1908)
 Question 262826: I don't even know how to set up this problem. I am not finding examples, can you help please? Events A and B are mutually exclusive events defined on a common sample space. If P (A) = 0.3 and P(A or B) = 0.75, find P(B). (B) Events A and B are defined on a common sample space. If P(A) = 0.30, P(B) = 0.50, and P(A or B) = 0.72, find P(A and B) Click here to see answer by Theo(3552)

 Question 262840: If no digit appears more than once, how many 4-digit numbers can be formed from the digits 2, 3, 4, 6, and 7 Click here to see answer by stanbon(60771)

 Question 262738: If sixty-four percent of all all airplanes arriving at an airport are late. What is the probabiltiy that exactly four planes will arrive late? Click here to see answer by stanbon(60771)

 Question 262744: The airborne speeds in miles per hour of 21 planes are shown below. Airplane speeds in miles per hour for 21 planes are: 366,533,386,367,380,409,526,387,516,401,513,428,429,415,460,449,475,492,500, 509,489 I am confused on exactly how to put the table together...do i make a column for say 300-400, 401-500, and so on?? Also I am unsure how to do this type of graph in excel...if anyone knows and can tell me where to find instructions on how to produce a graph like this i would greatly appreciate it :) Find the approximate values that correspond to the given percentiles by constructing a percentile graph: 9th, 20th, 45th, 60th, and 75th. Click here to see answer by stanbon(60771)

 Question 262859: Using the r calculated in problem 2c test the significance of the correlation coefficient using  = 0.01 and the claim rho = 0. Use the 7-steps hypothesis test shown at the end of this project. (References: example 7 page 505; end of section exercises 23 - 28 pages 510 - 511) (5 points) (Note: Round the computed t to 3 decimals.) 1. H0 : Ha : 2.  = 3. 4. the critical value(s) t0. 5. Rejection region: 6. Decision: 7. Interpretation: ************************ r= 0.915 -can you assist with this answer nw? Thanks.. another curious mind..Thanks! Click here to see answer by stanbon(60771)

 Question 262645: The diameters of oranges in a certain orchard are normally distributed with a mean of 4.85 inches and a standard deviation of 0.40 inches. Show all work. (A) What percentage of the oranges in this orchard have diameters less than 6.3 inches? (B) What percentage of the oranges in this orchard are larger than 4.75 inches? (C) A random sample of 100 oranges is gathered and the mean diameter obtained was 4.75. If another sample of 100 is taken, what is the probability that its sample mean will be greater than 4.75 inches? (D) Why is the z-score used in answering (A), (B), and (C)? (E) Why is the formula for z used in (C) different from that used in (A) and (B)? Click here to see answer by stanbon(60771)

 Question 262939: In a study of the life expectancy of 500 people in a certain geographic region,the mean age at death was 72.0 years, and the standard deviation was 5.3 years. If a sample of 50 people from this region is selected, find the probability that the mean life expectancy will be less than 70 years. They want all work to be shown and I don't even no where to begin. Thanks for your help Click here to see answer by stanbon(60771)

 Question 262934: the chances of having a girl or boy are about the same. Use a simulation to find the probability that a family that has three children will have two girls and one boy. Click here to see answer by stanbon(60771)

 Question 263049: if P(A)= 7/36, P(B)= 1/6, and P(A and B)= 0, what can you say about P(A or B)? Click here to see answer by stanbon(60771)

 Question 263053: A roulette wheel has 18 red slots and 18 black slots numbered alternately with the numbers 1 through 36. Two green slots are numbered 0 and 00. the winning number is determined by the slot into which a single marble rolls. Players are not allowed to bet on green. The house wins all bets if 0 or 00 comes up. what are the odds in favor of a number greater than 30 winning? Click here to see answer by stanbon(60771)

 Question 263036: If a student randomly guesses at 20 multiple-choice questions, find the probability thatthe student gets exactly four correct. Each question has four possible choices. Click here to see answer by richwmiller(10272)

 Question 263092: find the mean and standard deviation of 44,36,52,40,32,60,48,36 Click here to see answer by drk(1908)

 Question 263064: J.D. Power and Associates says that 60% of car buyers now use the Internet for research and price comparisons a. Find the probability that in a sample of 8 car buyers, all 8 will use the internet b. At least 5 c. More than 4 d. Find the mean and standard deviation of the probability distribution Click here to see answer by stanbon(60771)

 Question 263117: A company manufactures calculators in batchers of 64 and there is a 5% rate of defect. Find the mean number of defects per batch? Click here to see answer by stanbon(60771)

 Question 263045: Totally lost on this. Assume that the mean systolic blood pressure of normal adults is 120 mmHg and the standard deviation is 5.6. Assume a normal distribution. Thats one part Then they are asking if an individual is selected find the probability that the indivdual's pressure will be between 120 and 121.8 mmhg. Any clarification for these would be great. Thanks for all your help Click here to see answer by stanbon(60771)

 Question 263061: A quiz consists 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 drk(1908)

 Question 263018: Assume that 8 competitors in a race are 4 men and 4 women. All are equally fit. What is the probability the top 3 finishes will include exactly one woman? Click here to see answer by palanisamy(496)

 Question 263210: The A. B. Company buys calculators from a Korean supplier. The probability of a defective calculator is 10%. If three calculators are selected at random, what is the probability that at least one of the calculators will be defective? Click here to see answer by stanbon(60771)

 Question 263250: Two marbles are drawn without replacement from a box with 3 white, 2 green, 1 red, and 1 blue marble. Find the probability of the first marble being red and the second marble being white mathematically. Click here to see answer by Madgen(4)

 Question 263239: The A. B. Company buys calculators from a Korean supplier. The probability of a defective calculator is 10%. If three calculators are selected at random, what is the probability that all three of the calculators will be defective? Click here to see answer by mducky2(62)

 Question 263245: The fill weight of a certain brand of adult cereal is normally distributed with a mean of 920 grams and a standard deviation of 5 grams. If we select one box of cereal at random from this population, what is the probability that it will weigh less than 915 grams? Click here to see answer by stanbon(60771)

 Question 263244: A ski resort profits \$1,300,000 during a good winter with lots of snow. The resort has a loss of \$425,000 otherwise. The resort’s historical climate data suggests that the probability of a good winter with lots of snow during any given year is 50%. What is the expected profit for the ski resort? Click here to see answer by stanbon(60771)

 Question 263215: A ski resort profits \$1,500,000 during a good winter with lots of snow. The resort has a loss of \$500,000 otherwise. The resort’s historical climate data suggests that the probability of a good winter with lots of snow during any given year is 40%. What is the expected profit for the ski resort? Click here to see answer by stanbon(60771)

 Question 263212: An employer wants to set a time limit so that 95% of the employees will finish a job on time. Past history has shown that the time required to do the job is normally distributed and has a mean time of 30 minutes with a standard deviation of 8 minutes. How much time should the employer allow employees to finish the job? Click here to see answer by stanbon(60771)

 Question 263144: The production manager at Bellevue Steel, a manufacturer of wheelchairs, wants to compare the number of defective wheelchairs produced on the day shift with the number on the afternoon shift. A sample of the production from 6 day shifts and 8 afternoon shifts revealed the following number of defects. Assume this is a two sample “Unknown Variances, Assumed Equal”. The level of significance is 0.05. The standard deviation for Day is 1.4142 and the standard deviation for Afternoon is 2.2678. Day 5 8 7 6 9 7 Afternoon 8 10 7 11 9 12 14 9 1. Set up the null and alternative hypothesis. 2. Calculate the value of the test statistic. 3. What is the value of the test statistic? 4. What is the decision rule (DR)? 5. Reject Ho if (complete the DR in next box) 6. What is your decision regarding Ho? Accept or Reject Ho? Click here to see answer by stanbon(60771)

 Question 263339: in a group of n people (n<365) what is the probability two people have the same birthday (month,day) Click here to see answer by stanbon(60771)

 Question 263351: 48% of men consider themselves professional baseball fans. You randomly select 10 men and ask each if he considers himself a professional baseball fan. Find the probability that the number of men that consider themselves baseball fans is (a) exactly eight (b) at least eight (c) less than eight) Click here to see answer by stanbon(60771)

 Question 263402: 5) In classical hypothesis testing, the test statistic is to the critical value what the ________________. A. test statistic is to the p-value B. p-value is to alpha C. level of significance is to the test statistic D. critical value is to alpha Click here to see answer by stanbon(60771)

 Question 263403: 6) The Roman Senate has become concerned about the loyalty of the army in Gaul commanded by Julius Caesar. They claim that, of the 80,000 men in the army, at least 28,000 are foreign barbarians. Caesar believes there are fewer barbarians, so the Senate should not worry. He polls one legion of 1,000 men and finds that 340 of them are barbarians. What is the test statistic for this hypothesis test? A. (0.35-0.34)/100 B. (0.35-0.34)/0.2275 C. (0.34-0.35)/0.063 D. (0.34-0.35)/0.015 Click here to see answer by stanbon(60771)

 Question 263401: 4) You performed a right-tailed hypothesis test and your sample gave you a test statistic in the left tail. Which of the following is considered the appropriate next step in this test? A. Change the level of significance of your test. B. Fail to reject the null. C. Change the sample and do the test again. D. Change the direction of the hypothesis. Click here to see answer by stanbon(60771)

 Question 263400: 3) If a hypothesis test has a level of significance of 5%, that means if the null is true, we don’t reject it 5% of the time. A. True B. False Click here to see answer by stanbon(60771)

 Question 263399: 2) “µ = 17” is an appropriate null hypothesis. A. True B. False Click here to see answer by stanbon(60771)