The ages of a group of 135 randomly selected adult females have a standard deviation of 17.9 years. Assume that the ages of female statistics students have less variation than ages of females in the general population, so let sigmaequals17.9 years for the sample size calculation. How many female statistics student ages must be obtained in order to estimate the mean age of all female statistics students? Assume that we want 95% confidence that the sample mean is within one-half year of the population mean. Does it seem reasonable to assume that the ages of female statistics students have less variation than ages of females in the general population?
In: Math
1. A consumer group is testing camp stoves. To test the heating capacity of a stove, they measure the time required to bring 2 quarts of water from 50 degrees to boiling.
Two competing models are under consideration. Thirty-six stoves of each model were tested and the following results were obtained.
Model 1: mean time is 11.4 and standard deviation is2.5
Model 2: mean time is 9.9 and standard deviation is 3.0
In: Math
2. a. Use signifcance test to test the indicated claim. A standard aptitude test is given to several randomly selected programmers, and the scores are given below for the mathematics and verbal portions of the test. At the 0.05 level of significance, test the claim that programmers do better on the mathematics portion of the test.
Mathematics 447 540 427 456 527 449 477 498 425
Verbal 385 478 343 371 440 371 394 422 385
b. Find a 90% confidence interval for the difference of the mean.
In: Math
What criteria would you look at when conducting a statistical analysis to determine which online dating site(s) someone should use, and why? If you would not consider online dating for yourself, ask a friend who has been or is participating in online dating for their input. For example, do you think it is necessary to simply fill in the answers in the profile, such as height, body type, hair color, etc., and your preferences in these same categories for your match? Or do you think it is also necessary to answer the questions that can help find someone who may be more suited to your personality? These types of questions cover a variety of genres, such as relationships, sex, politics and law, and life and death.4 You can also find information online about statistics indicating which site yields the most success. Success may be determined by the site that yields the most number of dates, or the most marriages. In your response, share with your peers what success determinate you found or looked for. What sample size do you think you would need to determine which site is most likely to yield the greatest success? In your response, please provide a link to an article about dating sites or a link to dating site that explains what kind of data these sites provide.
In: Math
A study found that the mean amount of time cars spent in drive-throughs of a certain fast-food restaurant was
157.6157.6
seconds. Assuming drive-through times are normally distributed with a standard deviation of
3434
seconds, complete parts (a) through (d) below.Click here to view the standard normal distribution table (page 1).
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Click here to view the standard normal distribution table (page 2).
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(a) What is the probability that a randomly selected car will get through the restaurant's drive-through in less than
118118
seconds?The probability that a randomly selected car will get through the restaurant's drive-through in less than
118118
seconds is
nothing.
(Round to four decimal places as needed.)
(b) What is the probability that a randomly selected car will spend more than
210210
seconds in the restaurant's drive-through?The probability that a randomly selected car will spend more than
210210
seconds in the restaurant's drive-through is
nothing.
(Round to four decimal places as needed.)
(c) What proportion of cars spend between
22
and
33
minutes in the restaurant's drive-through?The proportion of cars that spend between
22
and
33
minutes in the restaurant's drive-through is
nothing.
(Round to four decimal places as needed.)
(d) Would it be unusual for a car to spend more than
33
minutes in the restaurant's drive-through? Why?
In: Math
Many studies have suggested that there is a link between exercise and healthy bones. Exercise stresses the bones and this causes them to get stronger. One study examined the effect of jumping on the bone density of growing rats. There were three treatments: a control with no jumping, a low-jump condition (the jump height was 30 centimeters), and a high-jump condition (60 centimeters). After 8 weeks of 10 jumps per day, 5 days per week, the bone density of the rats (expressed in mg/cm3 ) was measured. Here are the data. data190.dat
(a) Make a table giving the sample size, mean, and standard deviation for each group of rats. Consider whether or not it is reasonable to pool the variances. (Round your answers for x, s, and s_(x^^\_) to one decimal place.)
Group n x^^\_ s s_(x^^\_)
Control
Low jump
High jump
(b) Run the analysis of variance. Report the F statistic with its degrees of freedom and P-value. What do you conclude? (Round your test statistic to two decimal places and your P-value to three decimal places.)
F =
P =
Conclusion: There is statistically no/a significant difference between the three treatment means at the α = .05 level.
obs group g density 1 Control 1 616 2 Control 1 613 3 Control 1 609 4 Control 1 619 5 Control 1 664 6 Control 1 602 7 Control 1 571 8 Control 1 585 9 Control 1 600 10 Control 1 609 11 Lowjump 2 623 12 Lowjump 2 620 13 Lowjump 2 622 14 Lowjump 2 653 15 Lowjump 2 622 16 Lowjump 2 634 17 Lowjump 2 647 18 Lowjump 2 636 19 Lowjump 2 642 20 Lowjump 2 660 21 Highjump 3 639 22 Highjump 3 611 23 Highjump 3 586 24 Highjump 3 622 25 Highjump 3 610 26 Highjump 3 605 27 Highjump 3 626 28 Highjump 3 630 29 Highjump 3 605 30 Highjump 3 640
In: Math
According to the National Eye Institute, 8% of men are red-green colorblind. A sample of 125 men is gathered from a particular subpopulation, and 13 men in this sample are colorblind.(Without using z-value)
a. Is this statistically significant evidence that the proportion of red-green colorblind men is greater than the subpopulation than the national average with alpha = 0.05?
b. What is the maximum number of men that could have been colorblind in this sample that would lead you to fail to reject the null hypothesis?
c. Using 8% as the probability of being colorblind, find a 95% confidence interval for the number of men in a sample of 125 who are colorblind.
In: Math
What other examples can you think of where most people have more or less than the average? This is true of most things with a non-symmetric distribution (e.g., weight, math scores, marathon times) but it is nice to continue the theme of the video in terms of risk (e.g., most have below average risk of a automobile accident, death by violence, or even, say, getting a date).
In: Math
The percent of persons (ages five and older) in each state who
speak a language at home other than English is approximately
exponentially distributed with a mean of 8.76.
The lambda of this distribution is
The probability that the percent is larger than 3.24 is P(x ≥ 3.24) =
The probability that the percent is less than 9.79 is P(x ≤ 9.79) =
The probability that the percent is between 5.76 and 11.76 is P(5.76 ≤ x ≤ 11.76) =
In: Math
A concessions manager at the Tech versus A&M football game must decide whether to have the vendors sell sun visors or umbrellas. There is a 35% chance of rain, a 25% chance of overcast skies, and a 40% chance of sunshine, according to the weather forecast in college junction, where the game is to be held. The manager estimates that the following profits will result from each decision, given each set of weather conditions:
Decision Weather Conditions Rain 0.35 Overcast 0.25 Sunshine 0.40
Sun visors Rain $-400 Overcast $-200 Sunshine $1,500
Umbrellas Rain 2,100 Overcast 0 Sunshine -800
a. Compute the expected value for each decision and select the best one.
b. Develop the opportunity loss table and compute the expected opportunity loss for each decision.
In: Math
| Clinical depression is a serious disorder that affects millions of people. Depression often leads to alcohol as a means of easing the pain. A Gallup survey attempted to study the relationship between depression and alcohol. A random sample of adults was drawn and after a series of question each respondent was identified as a 1 = Nondrinker, 2 = moderate drinker, 3 = heavy drinker. Additionally, each respondent was asked whether they had ever been diagnosed as clinically depressed at some time in their lives (1 = Yes, 2 = No). Is there enough evidence to conclude that alcohol and depression are related? |
In: Math
A manufacturing company produces electric insulators. You define the variable of interest as the strength of the insulators. If the insulators break when in use, a short circuit is likely. To test the strength of the insulators, you carry out destructive testing to determine how much force is required to break the insulators. You measure force by observing how many pounds are applied to the insulator before it breaks. The data shown below represent the amount of force required to break a sample of 30 insulators. Complete parts a through c below. 9 10 7 7 15 19 22 24 15 35 15 30 25 22 30 31 28 29 39 62 10 6 42 40 15 22 23 24 25 25 Construct a 99% confidence interval for the population mean force.
In: Math
Time spent using e-mail per session is normally distributed, with mu equals μ=12 minutes and sigma equals σ=3 minutes. Assume that the time spent per session is normally distributed. Complete parts (a) through (d). b) If you select a random sample of 50 sessions, what is the probability that the sample mean is between 11.5 and 12 minutes?
In: Math
What’s the probability of getting no heads after flipping a fair coin 10 times? What’s the probability of getting no 3’s after rolling a fair 6-sided die 9 times? What’s the probability of getting a 4 at least once after rolling a fair 4-sided die 5 times? What’s the probability of getting a 5 exactly once after rolling a fair 8-sided die 7 times?
In: Math
Use the given degree of confidence and sample data to find a confidence interval for the population standard deviation σ. Assume that the population has a normal distribution. Weights of men: 90% confidence; n = 14, = 155.7 lb, s = 13.6 lb
A. 11.0 lb < σ < 2.7 lb
B. 10.1 lb < σ < 19.1 lb
C. 10.4 lb < σ < 20.2 lb
D. 10.7 lb < σ < 17.6 lb
In: Math