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Tutors Answer Your Questions about Probability-and-statistics (FREE)
Question 127665This question is from textbook fundamentals of maths
: A quiz show uses a fish bowl that contains nine balls, numbered one through nine, for selecting participants. A ball is selected at random. Find the probability that the number chosen is greater than 6?
i did it this way.
1,2,3,4,5,6,7,8,9,
p(greater than 6)= 7,8,and 9 =24 over 9. is this right.
Thanks for all your helpThis question is from textbook fundamentals of maths
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Question 127660: Please help! The probability is 1 in 4,000,000 that a single auto trip in the US will result in a fatality. Over a lifetime, an average US driver takes 50,000 trips.
A) what is the probability of a fatal accident over a lifetime?
This is what was figured out:
1death/4,000,000 trips = x deaths /50,000
4,000,000x = 50,000
x=50,000/4,000,000
x=.0125 or 1.25%
My class is an online course, materials are printed. No hard book provided.
Click here to see answer by stanbon(26259) |
Question 127695: I need help! Please provide a clear solution! Thank you so much!! :)
A driver approaching a toll booth has exactly two quarters, two dimes and two nickels in his pocket. He reaches into his pocket and randomly selects two of these coins. What is the probability that the coins that he selects will be at least enough to pay the 30-cent toll?
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Question 127702This question is from textbook Applied Statistics in Business and Economics
: 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.)This question is from textbook Applied Statistics in Business and Economics
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Question 127710This question is from textbook
: 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 apporporiate hypotheses. (b) Ovtain a test statistic and p-value. Interpret the results at level of significance .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?This question is from textbook
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Question 127645This question is from textbook Applie Statics in Business and Econmics
: I am totally stuck with this. Ant help would be appreicated. Thank you!!
Does Lovastain (a cholesterol-lowing drug) reduce the risk of heart attack? In 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. Interpretthe results as a=.01.
C. Is the difference large enough to be imporant?
E. What else would medical researches need to know before prescribing this drug widely?This question is from textbook Applie Statics in Business and Econmics
Click here to see answer by stanbon(26259) |
Question 127725: Please help me. This question is taken from the Stats and Econ Question # 9.54 I checked the answers and this one is not answered.
Faced with rising fax costs, a firm issued a guideline that transmissions of 10 pages or more should be sent by 2-day mail instead. Exceptions are allowed, but they want the average to be 10 or below. The firm examined 35 randomly chosen fax transmissions during the next year, yielding a sample mean of 14.44 with a standard deviation of 4.45 pages.
(a) At the .01 level of significance, is the true mean greater than 10?
(b) Use Excel to find the right-tail p-value.
Thank you for your kind assistance.
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Question 127724: 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 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? (See story.news.yahoo.com accessed
June 25, 2004.)
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Question 127788: 10.30 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.
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Question 127648This question is from textbook Applie Statics in Business and Econmics
: I have been working with someone else on this problem and we are both stuck. Can you please give any help to this problem. Thanks so much!!!!
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 trucks made 135, 035 rund and had 4 accidents.
At a=.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 imporant? if so, to whom, and why?
G. Is the normality assumption fulfilled? Explain.This question is from textbook Applie Statics in Business and Econmics
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Question 127605: 3.)A contest where the winning ticket belongs to the one contestant whose ticket has 1 letter (A-Z) followed by 3 digits (0-9) in the proper order.
-How many different tickets could be made for this contestant? Letters and numbers can be repeated.
-How many tickets could be made for this contest if letters and numbers cannot be repeated?
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Question 128009: I just want to know if my answers are correct.
State True or False
a) A collection of all the objects to be studied is a sample F
b) A subset or part of the subjects to be studied is a sample T
c) In a frequency distribution the class limits must overlap F
d) Pie charts are best used to plot numbers over a period of time F
e) A frequency distribution should have between 3 and 10 classes F
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Question 128008: Here is another problem that I don't understand. Can someone help me with this?
The following statistics provide information about the scores on a national mathematics exam.
Mean 312 | First Quartile 201
Median 296 | Third Quartile 423
Mode 326 | 49th Percentile 307
a) What score did half of the test takers surpass?
b) What was the most common score?
c) What percentage of the test takers scored 201 or better?
d) If Joe had a score of 307, explain the meaning of his score.
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Question 128007: I didn't know how to answer this question. Can someone help me? Thanks
A governor would like to find out how people in his state feel about state subsidized public art. How might a cluster sample be selected?
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Question 128116: Problem Two:
In designing a new dormitory, a progressive university wishes to determine where students prefer to study in order to provide appropriate space. A survey of 100 randomly selected undergraduate students shows that 33% prefer to study in their rooms.
(1) Construct a 95% confidence interval for the proportion of students who prefer to study in their rooms.
(2) If university has the option of making various sized rooms, what proportion of the rooms should be made larger to accommodate those who wish to study in their rooms?
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Question 128115: Problem One:
According to police records, from 1987 to 1995, the city of Davis, California experienced the following burglary rate (offenses per 1,000 residents for a given year):
(1) What is the mean burglary rate?
(2) What is the standard deviation of the burglary rate?
(3) What is the degree of freedom?
(4) What is the t-statistic @ 95% confidence?
(5) What is the standard error?
(6) What is the amount of error?
(7) What is the upper confidence bound per thousand offenses @ 95% confidence the mean annual burglary rate in Davis, California?
(8) What is the lower confidence bound per thousand offences @ 95% confidence the mean annual burglary rate in Davis, California?
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Question 128064This question is from textbook Applie Statics in Business and Econmics
: Can someone please help me with this one. Thanks so much!!!!
In a bumper test, three types of autos were deliberately crashed into a barrier at 5mp, and the resulting damage (in dollars) was estimated. Five test vehicles of each type were crashed, with the results shown below. Research question: Are the mean crash damages the same for these three vehicles?
Goliath= 1,600-760-880-1,950-1,220
Varmint= 1,290-1,400-1,390-1,850
Weasel=1,090-2,100-1,830-1,250-1,920
This question is from textbook Applie Statics in Business and Econmics
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Question 128371: Please help me. I need desperate help.
Biologists at the Long Beach aquarium would like to know if conditions at aquariums reduce the life span of dolphins. Dolphins live an average of 21 years in the wild with a standard deviation of 3 years. Furthermore, the lifespan of dolphins forms a normal distribution.
Because dolphins are exchanged with other aquariums and because some dolphins’ ages are unknown, the biologists were able to randomly select only 4 dolphins for the study. The four lived to the following ages: 17, 19, 20, 21. At a .05 significance level, can the biologists claim that dolphins living in captivity have a shorter life span than dolphins at sea?
Question 1: What is the null hypothesis?
Q2: What is the alternate hypothesis?
Q3: Which is the correct hypothesis test (e.g., Z-, t-, or F-test)?
Q4: Is this a directional or nondirectional test?
Q5: What is the test statistic?
Q6: What is the p-value?
Q7: What is your conclusion?
Q8: Is it possible that an error was committed? If so, which kind?
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Question 128355: Please kindly help me. I am stuck with this question and cannot move on. Thank you again for the help
Biologists at the Long Beach aquarium would like to know if conditions at aquariums reduce the life span of dolphins. Dolphins live an average of 21 years in the wild with a standard deviation of 3 years. Furthermore, the lifespan of dolphins forms a normal distribution.
Because dolphins are exchanged with other aquariums and because some dolphins’ ages are unknown, the biologists were able to randomly select only 4 dolphins for the study. The four lived to the following ages: 17, 19, 20, 21. At a .05 significance level, can the biologists claim that dolphins living in captivity have a shorter life span than dolphins at sea?
Question 1: What is the null hypothesis?
Q2: What is the alternate hypothesis?
Q3: Which is the correct hypothesis test (e.g., Z-, t-, or F-test)?
Q4: Is this a directional or nondirectional test?
Q5: What is the test statistic?
Q6: What is the p-value?
Q7: What is your conclusion?
Q8: Is it possible that an error was committed? If so, which kind?
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Question 128589: Each question of a 5-question multiple choice exam has 3 possible answers. Suppose a student picks an answer at random for each question. Find the probability the student selects the correct answer on none of the questions.
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Question 128588: Mr. and Mrs. J. B. Davis just moved into a new home and need to purchase kitchen appliances. The Davises are going to purchase a refrigerator, a stove, and a dishwasher. They have a number of choices for each appliance.
For Refrigerator: General Electric, Maytag, Kenmore, Acme For Stove: General Electric, Frigidaire, Roper, Acme For Dishwasher: General Electric, KitchenAid, WhirlPool
Determine the number of points in the sample space.
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Question 128585: An individual can be classified by gender as male, female, by hair color as black, blonde, brown; by eye color as black, brown, green. How many different classifications are possible (for example, male, with black hair, and green eyes)?
Thank you in advance
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Question 128630This question is from textbook fundamentals of maths
: Once again i am asking for your help.
A quarter is flipped and the out come is noted. If a head results, then a die is rolled. If a tail results, then the quarter is flipped a second time.
a. How many different outcomes are possible?
b. Make a tree diagram to list the sample space for the possible outcomes.
I am not putting all my work on you, but my brain just went blank. Thanks for all your help.This question is from textbook fundamentals of maths
Click here to see answer by stanbon(26259) |
Question 128602This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
: 15.18 Sixty-four students in an introductory college economics class were asked how many credits they had earned in college, and how certain they were about their choice of major. Research question: At α = .01, is the degree of certainty independent of credits earned?
Credits Earned Very Uncertain Somewhat Certain Very Certain Row Total
0–9 12 8 3 23
10–59 8 4 10 22
60 or more 1 7 11 19
Col Total 21 19 24 64
15.22 A student team examined parked cars in four different suburban shopping malls. One hundred vehicles were examined in each location. Research question: At α = .05, does vehicle type vary by mall location? (Data are from a project by MBA students Steve Bennett, Alicia Morais, Steve Olson, and Greg Corda.)
Vehicle Type Somerset Oakland Great Lakes Jamestown Row Total
Car 44 49 36 64 193
Minivan 21 15 18 13 67
Full-sized Van 2 3 3 2 10
SUV 19 27 26 12 84
Truck 14 6 17 9 46
Col Total 100 100 100 100 400
15.24 High levels of cockpit noise in an aircraft can damage the hearing of pilots who are exposed to this
hazard for many hours. A Boeing 727 co-pilot collected 61 noise observations using a handheld
sound meter. Noise level is defined as “Low” (under 88 decibels), “Medium” (88 to 91 decibels),
or “High” (92 decibels or more). There are three flight phases (Climb, Cruise, Descent). Research
question: At α = .05, is the cockpit noise level independent of flight phase? (Data are from
Capt. Robert E. Hartl, retired.)
Noise Level Climb Cruise Descent Row Total
Low 6 2 6 14
Medium 18 3 8 29
High 1 3 14 18
Col Total 25 8 28 61
15.28 Can people really identify their favorite brand of cola? Volunteers tasted Coca-Cola Classic,
Pepsi, Diet Coke, and Diet Pepsi, with the results shown below. Research question: At α = .05, is
the correctness of the prediction different for the two types of cola drinkers? Could you identify
your favorite brand in this kind of test? Since it is a 2 × 2 table, try also a two-tailed two-sample
z test for π1 = π2 (see Chapter 10) and verify that z2 is the same as your chi-square statistic.Which
test do you prefer? Why? (Data are from Consumer Reports 56, no. 8 [August 1991], p. 519.)
Correct? Regular Cola Diet Cola Row Total
Yes, got it right 7 7 14
No, got it wrong 12 20 32
Col Total 19 27 46
This question is from textbook APPLIED STATISTICS IN BUSINESS AND ECONOMICS
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Question 128645: 4. Problem One: This question is due on day 4.
According to police records, from 1987 to 1995, the city of Davis, California experienced the following burglary rate (offenses per 1,000 residents for a given year):
1987 - 15.8
1988 - 17.2
1989 - 16.5
1990- 15.5
1991 - 17.1
1992 - 18.6
1993 - 21.4
1994 - 29.0
1995 - 19.3
(1) What is the mean burglary rate?
(2) What is the standard deviation of the burglary rate?
(3) What is the degree of freedom?
(4) What is the t-statistic @ 95% confidence?
(5) What is the standard error?
(6) What is the amount of error?
(7) What is the upper confidence bound per thousand offenses @ 95% confidence the mean annual burglary rate in Davis, California?
(8) What is the lower confidence bound per thousand offences @ 95% confidence the mean annual burglary rate in Davis, California?
Click here to see answer by stanbon(26259) |
Question 128644: A random sample of 10 miniature Tootsie Rolls was taken from a bag. Each piece was weighed on a very accurate scale. The results in grams were 3.087 3.131 3.241 3.241 3.270 3.353 3.400 3.411 3.437 3.477
(a) Construct a 90 percent confidence interval for the true mean weight. (b) What sample size would be necessary to estimate the true weight with an error of ± 0.03 grams with 90 percent confidence? (c) Discuss the factors which might cause variation in the weight of Tootsie Rolls during manufacture. (Data are from a project by MBA student Henry Scussel.)
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Question 128643: A local company wants to evaluate their quality of service by surveying their customers. Their budget limits the number of surveys to 100. What is their maximum error of the estimated mean quality for a 95% level of confidence and an estimated standard deviation of 5?
A) 0.9604
B) 0.9800
C) 1.96
D) 5%
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Question 128642: David's gasoline station offers 4 cents off per gallon if the customer pays in cash and does not use a credit card. Past evidence indicates that 40% of all customers pay in cash. During a one-hour period twenty-five customers buy gasoline at this station.
(4) What is the probability that at least ten pay in cash?
A) 0.416
B) 0.575
C) 0.586
D) 0.425
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