Suppose that a 95% confidence interval for the average number of minutes a regular customer uses with a cellphone in a month is 110 plus or minus 35 minutes. What are the lower and upper boundaries for this confidence interval?.

Q: Define why a confidence interval makes clear that one should not accept the null hypothesis

A: Despite the size of the sample, it is not possible for an individual to conclude that the null…

Q: Suppose a consumer advocacy group wants to conduct a survey to find if the proportion of consumers…

A:

Q: Suppose a different police department says their SRS resulted in a 95% confidence interval of 10.1%…

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Q: A stock market analyst notices that in a certain year, the price of IBM stock increased on 131 out…

A: It is given that the price of IBM stock increased on 131 out of 252 trading days.

Q: Suppose the desired confidence level is fixed, then what is the effect of a larger sample size on…

A:

Q: If a researcher found that the margin of error =0.9 and the sample mean from the study was 17.7,…

A: Given, A researcher found that the margin of error ME  = 0.9 and  The sample mean u = 17.7 Find the…

Q: confidence interval for the proportion of college students who have texted during class was found to…

A: Given

Q: If a 90% confidence interval for the difference of means μ 1 − μ 2 contains all negative values,…

A: The mean of first population is denoted as μ1 and mean of second population is denoted as μ2.

Q: What are the conditions for a confidence interval?

A: A confidence interval tells the possible range around the estimate and also how stable the estimate…

Q: 1. How is the expected length of a confidence interval related to the margin of error?

A: here use basic of confidence interval

Q: Suppose we know that a confidence interval for a population mean is (53, 67), with a margin of error…

A:

Q: Explain why a 100% confidence interval for µ can never be constructed from a sample.  Hint:  What…

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Q: If a 95% confidence interval contains 0, so will the 99% confidence interval. True False3

A: Solution: As the confidence level increases the margin of error increases. This leads to the…

Q: confidence interval for the mean of five measurements is smaller than for a single result.

A: Here we use confidence interval formula for explanations as given in step 2

Q: What can we do to make a confidence interval narrower without changing the confidence level?

A: Confidence interval:  A range of values such that the population parameter can expected to contain…

Q: Suppose we take a SRS of high school seniors and get a 95% confidence interval that 250 to 278…

A:

Q: Suppose the average US salary is $41,000. If a sample of 50 people are randomly surveyed then there…

A: Given Average=41000

Q: if for some reason it was not possible to obtain the 99% confidence interval from SPSS, how could…

A: Given information: Confidence level=99%=0.99α=1%=0.01

Q: We would not develop a confidence interval on the population mean, µ, if we had all the population…

A: We develop confidence interval of the population mean when we do not have the access to the…

Q: What proportion of college students earn their undergraduate degrees in four years? A college…

A: The formula of the margin of error when the limits given are,

Q: "if the confidence level or P-value does not change very much when the conditions for use of the…

A: In general, t-test is used for small samples and samples are normally distributed. It is used when…

Q: Explain the steps in computing a confidence interval for ρ?

A: Introduction: The steps to construct a confidence interval in general are: Identify a sample…

Q: What are the the conditions for the confidence interval to be valid?

A: Given that: Mean response of 300 students and survey result give a 95% confidence interval for mean.…

Q: What is A confidence interval for μ?

A:

Q: What happens in a confidence interval if the size of the sample increases the length of interval

A: WIdth of a confidence interval = W Margin of error = E

Q: What effect does increasing the sample size have on the width of a confidence interval? I know that…

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Q: The police department wants to reduce the margin of error for their 95% confidence interval. If they…

A: Here Given  The police department wants to reduce the margin of error for their 95% confidence…

Q: What is Confidence Intervals for μ1 − μ2?

A:

Q: Suppose a drug for stomach discomfort is tested on 75 subjects, and the mean time for it to take…

A: Given: Sample size n = 75 Sample mean X = 200 Population standard deviation σ = 30 Formula Used:…

Q: 9. How can you make a 95% confidence interval smaller without changing the confidence level?

A: There are several number of ways to reduce the size of confidence interval without making any…

Q: Suppose a drug for stomach discomfort is tested on 50 subjects, and the mean time for it to take…

A: To find the confidence interval we will use z distribution because the population standard deviation…

Q: 1. How can you make a 95% confidence interval smaller without changing the confidence level?

A: Confidence interval is an interval such that the probability of the unknown parameter to be included…

Q: If there was a 95% confidence interval of say, (0.48, 0.68), about a product being preferred by…

A: The confidence interval at 100 (1 – α) % confidence level gives us an interval estimate about the…

Q: Suppose that we want a 95% confidence interval for π = proportion of defective if we observe 4…

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Q: Would represent a 90% confidence interval for the average highway mileage of all Smart Cars?

A: we need to find the confidence interval of the mean GIVEN mean=47 S.D=5 n=15

Q: A 90% confidence interval for the difference between the proportion of college students who use…

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Q: When calculating a confidence interval for one sample with a continuous outcome and the sample…

A: It is given that the sample size is greater than 30.

Q: Would it be reasonable to develop a confidence interval from these data to show the mean number of…

A: John is interested to know the number of hours children under 12 years if age watched TV per day.…

Q: When computing a confidence interval, the size of the error term depends on what?

A: The formula to calculate the error term for confidence interval is as follow:

Q: What is meant by saying that a 1−α confidence interval is a. exact? b. approximately correct?

A: a) 1−α confidence interval is Exact means that the probability that the unknown value of population…

Q: What is the formula for CONFIDENCE INTERVAL (CI) FOR μ1 – μ2 (TWO INDEPENDENT SAMPLES)?

A: From the given information, consider two independent samples drawn randomly with sample sizes n1 and…

Q: Suppose you compute a 93% confidence interval. What will happen to the confidence interval if you…

A: Increasing the confidence level increases the margin of error. This will increase the width or range…

Q: Suppose you construct a 90% confidence interval for the true population mean GPA of students at Taft…

A: Given that  We constructed 90% confidence interval for true population mean GPA of students at Taft…

Q: Why is it that when we increase our confidence level in a confidence interval that the interval gets…

A: Confidence inteval is calculated with mean/proportion and standard error. While the value of…

Q: What will happen to the precision of a confidence interval if the variability of a sample gets…

A: Farmula  Length of Confidence interval=2xZcxσ/√n

Q: What is a confidence interval

A: The confidence interval in statistics is a type of estimation computed from the statistics of the…

Q: suppose that in sampling for the population proportion, it is found that 20 out of 100 items are…

A:

Q: Imagine that the confidence interval around a candidate's popularity score is [37.22,48.86],what is…

A: The confidence interval provides an estimated range of values that includes an unknown population…

Q: The general form of a confidence interval is inferred as

A: Confidence interval : The probability that a parameter will fall between two values around the mean…