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
Describe a scenario where a researcher could use a Goodness of Fit Test to answer a research question. Fully describe the scenario and the variables involved and explain the rationale for your answer. Why is that test appropriate to use? (3 points)
Describe a scenario where a researcher could use a Test for Independence to answer a research question. Fully describe the scenario and the variables involved and explain the rationale for your answer. Why is that test appropriate to use? (3 points)
The Goodness of Fit Test and Test for Independence both use the same formula to calculate chi-square. Why? I.e., explain the logic of the test. (3 points)
Compare the Goodness of Fit Test and the Test for Independence in terms of the number of variables and levels of those that can be compared. In what ways are they similar or different? (3 points)
Describe how the Test for Independence and correlation are similar yet different. (3 points)
In: Math
It is thought that basketball teams that make too many fouls in a game tend to lose the game even if they otherwise play well. Let x be the number of fouls more than (i.e., over and above) the opposing team. Let y be the percentage of times the team with the larger number of fouls wins the game.
|
x |
1 |
4 |
5 |
6 |
|
y |
51 |
42 |
33 |
26 |
Complete parts (a) through (e), given Σx = 16, Σy = 152, Σx2 = 78, Σy2 = 6130, Σxy = 540, and
r ≈ −0.966.
(a) Draw a scatter diagram displaying the data.
(b) Verify the given sums Σx, Σy,
Σx2, Σy2, Σxy, and
the value of the sample correlation coefficient r. (Round
your value for r to three decimal places.)
|
Σx = |
|
|
Σy = |
|
|
Σx2 = |
|
|
Σy2 = |
|
|
Σxy = |
|
|
r = |
(c) Find x, and y. Then find the equation of the
least-squares line = a + bx. (Round your answers
for x and y to two decimal places. Round your
answers for a and b to three decimal places.)
|
x |
= |
|
|
y |
= |
|
|
= |
+ x |
(d) Graph the least-squares line. Be sure to plot the point (x, y) as a point on the line.
(e) Find the value of the coefficient of determination r2. What percentage of the variation in y can be explained by the corresponding variation in x and the least-squares line? What percentage is unexplained? (Round your answer for r2 to three decimal places. Round your answers for the percentages to one decimal place.)
|
r2 = |
|
|
explained |
% |
|
unexplained |
% |
(f) If a team had x = 3 fouls over and above the opposing
team, what does the least-squares equation forecast for y?
(Round your answer to two decimal places.)
%
In: Math
Assuming the population is normally distributed, construct a 95% confidence interval for the population mean, based on the following sample of size n = 7:
1 2 3 4 5 6 7
The mean is 4 and Standard Deviation 2.16
1. What is the lower boundary of the interval to two decimal places?
2. What is upper boundary of the interval to two decimal.
In: Math
In: Math