




Card 12 / 20:
Suppose that an accounting firm does a study to determine the time needed to complete one person’s tax forms. It randomly surveys 100 people. The sample mean is 23.6 hours. There is a known standard deviation of 7.0 hours. The population distribution is assumed to be normal.
x ¯ =________ σ =________ n =________In words, define the random variables X and X ¯ .Which distribution should you use for this problem? Explain your choice.Construct a 90% confidence interval for the population mean time to complete the tax forms. State the confidence interval. Sketch the graph. Calculate the error bound.If the firm wished to increase its level of confidence and keep the error bound the same by taking another survey, what changes should it make?If the firm did another survey, kept the error bound the same, and only surveyed 49 people, what would happen to the level of confidence? Why?Suppose that the firm decided that it needed to be at least 96% confident of the population mean length of time to within one hour. How would the number of people the firm surveys change? Why?

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Questions & Answers
7.The following data give thenumber of car thefts that occurred in a city in the past 12 days.
63711438726915
Calculate therange, variance, and standard deviation.
express the confidence interval 81.4% ~8.5% in interval form
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The information is given as, 30% of customers shopping at SHOPNO will switch to DAILY SHOPPING every month on the other hand 40% of customers shopping at DAILY SHOPPING will switch to other every month. What is the probability that customers will switch from A to B for next two months?
Calculate correlation coefficient, where SP(xy) = 144; SS(x) = 739; SS(y) = 58.
(2 Points)
The information are given from a randomly selected sample of age of COVID19 patients who have already survived. These information are collected from 200 persons. The summarized information are as, n= 20; ∑x = 490; s^2 = 40. Calculate 95% confident interval of mean age.
Ashfat
The mode of the density of power of signal is 3.5. Find the probability that the density of a random signal will be more than 2.5.
Ashfat
The average time needed to repair a mobile phone set is 2 hours. If a customer is in queue for half an hour, what is the probability that his set will be repaired within 1.6 hours?
Ashfat
A quality control specialist took a random sample of n = 10 pieces of gum and measured their thickness and found the mean 9 and variance 0.04. Do you think that the mean thickness of the spearmint gum it produces is 8.4
3. The following are the number of mails received in different days by different organizations:
Days (x) : 23, 35, 38, 50, 34, 60, 41, 32, 53, 67.
Number of mails (y) : 18, 40, 52, 45, 32, 55, 50, 48, 26, 25.
i) Fit a regression line of y on x and test the significance of regression.
ii) Estimate y
The number of problem creating computers of two laboratories are as follows:
Number of computers: 48, 6, 10, 12, 30, 11, 49, 17, 10, 14, 38, 25, 15, 19, 40, 12.
Number of computers: 12, 10, 26, 11, 42, 11, 13, 12, 18, 5, 14, 38.
Are the two laboratories similar in respect of problem creating compute
Is the severity of the drug problem in high school the same for boys and
girls? 85 boys and 70 girls were questioned and 34 of the boys and 14 of the girls admitted to
having tried some sort of drug. What can be concluded at the 0.05 level?
a quality control specialist took a random sample of n=10 pieces of gum and measured their thickness and found the mean 7.6 and standered deviation 0.10. Do you think that the mean thickness of the spearmint gum it produces is 7.5?
99. A one sample, onetail ttest is conducted and the test statistic value is calculated to be 2.56.
The degrees of freedom for the test are 10. Which of the following conclusions for the test would
be correct?
a
A one sample, onetail ttest is conducted and the test statistic value is calculated to be 2.56.
The degrees of freedom for the test are 10. Which of the following conclusions for the test would
be correct?
Niaz
what is null Hypothesis
Niaz
what is null Hypothesis
Niaz
when median is greater than mode?
is this app useful
Worthy
when tail is positive
Jungjoon
I'm struggling to type it's on my laptop...statistics
Yoliswa
types of averages .mean median mode quarantiles MCQ question
Out of 25 students, 15 are male. Is the overall proportion of male students 0.7 in AIUB?
(4 Points)
15/25=0.6 or 60% standard calculation
Andrea
A quality control specialist took a random sample of n = 10 pieces of gum and measured their thickness and found the mean 7.6 and variance 0.01. Do you think that the mean thickness of the spearmint gum it produces is 7.5?
(4 Points)
Omer
10 gums
mean = 7.6
variance= 0.01
standard deviation= ?
what us the data set?
Andrea
Source:
OpenStax, Introductory statistics. OpenStax CNX. May 06, 2016 Download for free at http://legacy.cnx.org/content/col11562/1.18
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