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

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 Question 379705: Give the coefficient of the third term in the expansion of each of the following. (x+2y)^5 Click here to see answer by Edwin McCravy(9717)

 Question 379774: Please explain what is wrong and why. If a correlation coefficient of r = 0.642 was found between two variables in a sample of paired data that were measured in feet, the value of r would change by a factor of twelve if the data were converted to inches and r was computed again. Click here to see answer by stanbon(60771)

 Question 379773: Please explain what is wrong and why. Using data from Boston, Massachusetts, a test of independence is run on the claim that ice cream sales per month and the number of car wrecks per month are independent. The claim is rejected. Using number of car wrecks as the x variable and ice cream sales as the y variable, an r value of r=0.923 is then computed and shown to exceed the critical value for this data. The data is double checked and verified. This shows that car wrecks cause ice cream sales. Click here to see answer by stanbon(60771)

 Question 379842: if there are 2 red, 4 green and 6 blue m&m's left in a packet, what is the probability of next picking a green one? Click here to see answer by richard1234(5390)

 Question 379910: what probability does a person with 12 raffle tickets have of winning if 200 tickets were sold Click here to see answer by user_dude2008(1861)

 Question 379936: 7) The age of student are normally distributed with a mean of 25 and a standard deviation of 4.25. If a student is chosen at random, what is the probability that : a) THE student age is at least 27 b) THE student age is between 26 and 30 Click here to see answer by robertb(4012)

 Question 379954: At a large department store, the average number of years of employment for a cashier is 5.7 with a standard deviation of 1.8 years. If the number of years of employment at this department store is normally distributed, what is the probability that a cashier selected at random has worked at the store for over 10 years? A)0.4916 B)0.9916 C)0.0084 D)0.0054 I have tried, but think I am using the wrong formula? I tried z=(x-mu)/o (<--standard deviation) z=10-5.7/1.8 = 2.38 Using Table E I get 0.4913. I then subtract from 0.5000 since we are looking for MORE than 10 years and I get 0.0087. However, this isn't a choice listed above. So I know I am missing something somewhere. Help would be appreciated. Thanks! Click here to see answer by jim_thompson5910(29613)

 Question 379994: a bag contains eleven discs numbered 1 to 11. two discs are selected at random with replacement. what is the probability that the sum is even? Click here to see answer by stanbon(60771)

 Question 379873: 3. Indicate whether the given statement could apply to a data set consisting of 1,000 values that are all different. a. The 29th percentile is greater than the 30th percentile. Yes or No b. The median is greater than the first quartile. Yes or No c. The third quartile is greater than the first quartile. Yes or No d. The mean is equal to the median. Yes or No e. The range is zero. Yes or No Click here to see answer by stanbon(60771)

 Question 380086: A report showed that 20% of the batteries produced in a factory were faulty. What is the probability that a box of 10 batteries produced in this factory will contain exactly 2 faulty batteries? Click here to see answer by robertb(4012)

 Question 380162: what formula shall I use to calculate the mean, median, and mode of a set of data that contains 36 scores? Click here to see answer by solver91311(18785)

 Question 380195: a child has 5 wooden blocks. He arranged it in a row and named it 1,2,3,4,5. What is the probability in numbered form that it is... Less than 20,000? More than 40,000? Click here to see answer by stanbon(60771)

 Question 376566: * A manufacturing process has 100 customer orders to fill. Each order requires one component part that is purchased from a supplier. However, typically 2% of the components are defective, and the components can be assumed to be independent. i) If the manufacturer stocks 100 components, what is the probability that the 100 orders can be filled without reordering components? ii) If the manufacturer stocks 102 components, what is the probability that the 100 orders can be filled without reordering components? iii) If the manufacturer stocks 105 components, what is the probability that the 100 orders can be filled without reordering components? Click here to see answer by Mech_Engineer(1)

 Question 380282: Find the critical t-value that corresponds to 98% confidence. Assume 6 degrees of freedom. Click here to see answer by stanbon(60771)

 Question 380242: A study showed 118 instances of breast cancer among 3,033 mothers who used diethylstibestrol (DES), an estrogen-like substance formerly used to prevent miscarriage, compared with 80 cases in 3,033 unexposed women comprising a control group. At the 0.02 level of significance, was the incidence of cancer greater in the DES users? Click here to see answer by stanbon(60771)

 Question 380316: Use the normal approximation to estimate the probability that a group of 20 wins. You will have to find the expected amount that you win and the standard deviation. Click here to see answer by stanbon(60771)

 Question 380341: Suppose the life of a certain brand of vacuum cleaner is normally distributed with a mean life of 12 years and a standard deviation of 4 years. A vacuum cleaner is randomly chosen. Find the probability that is will last between 6 to 12 years. Click here to see answer by stanbon(60771)

 Question 380343: Suppose the life of a certain brand of vacuum cleaner is normally distributed with a mean life of 12 years and a standard deviation of 4 years. A vacuum cleaner is randomly chosen. For how many years should the manufacturer warranty its vacuum cleaners if it is willing to replace only 1% of the vacuum cleaners it sells. Click here to see answer by stanbon(60771)

 Question 380342: the probability of the event; rolling four fair dice and getting an odd number on all four dice. Click here to see answer by richard1234(5390)

 Question 380339: Suppose the life of a certain brand of vacuum cleaner is normally distributed with a mean life of 12 years and a standard deviation of 4 years. A vacuum cleaner is randomly chosen. Find the probability that it will last more than 16 years. Click here to see answer by ewatrrr(11176)

 Question 380337: Suppose the life of a certain brand of vacuum cleaner is normally distributed with a mean life of 12 years and a standard deviation of 4 years. A vacuum cleaner is randomly chosen. Find the probability that is will last more than 10 years. Click here to see answer by ewatrrr(11176)

 Question 380227: There are entrees available at a restaurant. From these, Archie is to choose for his party. How many groups of entrees can he choose, assuming that the order of the entrees chosen does not matter? Click here to see answer by stanbon(60771)

 Question 380411: Use Table 3 in Appendix B to find the probability of z = 0.15. Click here to see answer by richard1234(5390)

 Question 380361: I just can't figure this one out and do not understand the example in our book! A local newspaper recently conducted a survey of 400 households in the community to determine the number of daily newspapers that were being delivered to the residence. Results were used to obtain the following probability distribution: X 0 1 2 3 4 or more P(x) 0.15 0.35 0.35 0.10 0.05 What is the probability that a household receives at most 2 daily papers? Click here to see answer by jim_thompson5910(29613)

 Question 380422: Let the random variable X follow a normal distribution with mean μ = 50 and variance σ2 = 25. a) Find the probability that X is greater than 58. b) Find the probability that X is greater than 46 and less than 60. c) If you draw a sample of size n=20 from the X population described above, what is the probability that the sample variance, s2, is larger than 30? d) Imagine a symmetric interval about the mean (μ±c) of the distribution described above. Find the value for c such that the probability is approximately 0.1 that X falls in this interval. Click here to see answer by stanbon(60771)

 Question 380463: You are dealt two cards successively (without replacement) from a shuffled deck of 52 playing cards. Find the probability tht both cards are black. Click here to see answer by stanbon(60771)

 Question 380461: which 95% confidence interval has the higher S, sample standard deviation? why? (1000, 2000) or (999, 2001) Click here to see answer by robertb(4012)

 Question 380504: There is a die with 10 faces. It is not known that fair or not. 2 captains want to toss die for batting selection. What is the possible solution among the following? a) If no. is odd it is head, if no. is even it is tail b) If no. is odd it is tail, if no. is even it is head c) Toss a die until all the 10 digits appear on top face. And if first no. in the sequence is odd then consider it as tail. If it is even consider it as head. Click here to see answer by edjones(7794)

 Question 380501: Use the given information to find the indicated probability. A and B are mutually exclusive. P(A) = .7, P(B) = .1. Find P((A ∪ B)'). P((A ∪ B)') = 1Your answer is incorre Click here to see answer by edjones(7794)

 Question 380499: Use the given information to find the indicated probability. A ∩ B = Ø, P(B) = .34, P(A ∪ B) = .34. Find P(A). P(A) = 1 Click here to see answer by edjones(7794)

 Question 380506: According to the New York Times/CBS poll of March, 2005, 56% agreed that Social Security taxes should be raised if necessary to keep the system afloat, and 41% agreed that it would be a good idea to invest part of their Social Security taxes on their own. What is the largest percentage of people who could have agreed with at least one of these statements? 1% What is the smallest percentage of people who could have agreed with at least one of these statements? 2% Click here to see answer by edjones(7794)

 Question 380491: There are 10 puppies in a cage, of which 6 are male and 4 are female. If you select three puppies at random, what is the probability that they will be the same gender? Click here to see answer by edjones(7794)

 Question 380334: On average, the probability that a computer breaks down in its second year of use is 0.05, and the average repair cost is \$300 per computer per year. If a salesperson sells a second year extended warranty policy for \$50, how much money is the policy issuer making per computer? Click here to see answer by edjones(7794)

 Question 380329: A certain reliability defect can be detected only with a destructive test. However, quality control has developed a nondestructive test that a product with the defect will fail 95% of the time. Those without the defect pass the test 95% of the time. Quality control proposes using the test as a 100% screening on all of the products. Products that fail the screening will not be replaced. If 2% of the product has the defect, what will be the percent of defective products that will get passed the screening? First, construct a table of the form below for listing all the possible probabilities, where intersections, such as P(F) and P(D) are found by finding P(F|D) * P(D), and so on. Note: P(F) gives the probability of failure of the screening, P(F’) is the probability of not failing the screening, P(D) is probability the product is defective, and P(D’) is the probability that the product is not defective. Remember that the probabilities must sum to 1 in the bottom-right corner. Click here to see answer by edjones(7794)

 Question 380535: what is the probability of getting 9 cards of same in a hand out of 52 cards? Click here to see answer by Fombitz(13828)

 Question 380508: Sangakara and Ponting selects batting by using a dice, but dice is biased. So to resolve, Ponting takes out a coin. What is the probability that coin shows correct option? a)1/2 b)1/6 c)1/12 d)6/10 Click here to see answer by Fombitz(13828)

 Question 380419: To qualify for security officers training, recruits are tested for stress tolerance. The scores are normally distributed, with a mean of 62 and a standard deviation of 8. If the only top 15% of recruits are selected, find the cut off score. Click here to see answer by Fombitz(13828)

 Question 380537: Hello¡ I am sorry, but i really need help with this problem. i have no idea of how to do it... Thank you very much. Exercise 1: A pharmaceutical company is concerned that the impurity concentration in pills does not exceed 2%. It is known that from a particular production run, impurity concentrations follow a normal distribution with standard deviation 0.3%. A random simple of 64 pills from a production run was checked and the sample mean impurity concentration was found to be 2.06%. a)Test at the 5% level the null hypothesis that the population mean impurity concentration is 3%. b)Find the probability of a 5%-level test rejecting the null hypothesis when the true mean impurity concentration is 2.10%. Click here to see answer by stanbon(60771)

 Question 380650: Let a be the last digit of your social security number if it is not zero. In the latter case, let a=1. Let the random variable X be Find the probability that X is larger than 2.5. Let Y be a random variable which is independent of X but has the same distribution. Find Click here to see answer by stanbon(60771)

 Question 380600: 12 members of a team want to use a spaceship to parachute somewhere. The probability of a successful jump is .7980 meaning that there is a one chance in five that someone would be badly hurt. However, given a successful jump, the probability of expedition success was .9943. Examine the probability .7980 of a successful jump. If you were one of the 12 members of the team, what is the probability that you would successfully complete your jump? In other words if the probability of a successful jump by all 12 members is .7980, what is the probability that a single member could successfully complete the jump? Click here to see answer by stanbon(60771)

 Question 380538: Please¡ i do really need help¡ Exercise 2: Several drugs are used to treat diabetes. A sales specialist for a leading pharmaceutical company randomly sampled the records of 10 sales districts to estimate the number of new prescriptions that had been written during a particular month for her company’s new diabetes drug. The numbers of new prescriptions were as follows: 210, 240, 190, 275, 290, 265, 312, 284, 261, 243. a)Find a 90% confidence interval for the average number of new prescriptions written for this new drug among all sales district. What are the assumptions? b)Calculate the widths of the 95% and 98% confidence intervals c)Assuming that the confidence level remains constant, what sample size is needed to reduce by half the margin of error of the confidence interval in part (a)? Click here to see answer by stanbon(60771)