The mean reading speed of a random sample of 81 adults is 320 words per minute. Find a 90% confidence interval for the mean reading speed of all adults if it is known that the standard deviation for all adults is 45 words per minute.

Q: A survey of 100 retailers revealed that the mean after-tax profit was $80,000. Assuming that the…

A: Given data,n=100σ=15,000x=80,000z-value at 95% confidence is Zc=1.96

Q: Use these data and a population standard deviation of 1.11 to construct a 98% confidence interval to…

A: The sample of 36 women's who had babies in the hospital during the past year is taken. The…

Q: Find the value of ta for a 99% confidence interval when sample size is 30

A: Hi! Thank you for the question, As per the honor code, we are allowed to answer one question at a…

Q: Find the 95% confidence interval for the mean difference of the tests, and explain it.

A: Test - 1 (X) Test-2 (Y) (x-xbar) (x-xbar)^2 (y-ybar) (y-ybar)^2 1.2 1.4 -0.31111 0.09679 -0.24444…

Q: Find a 90% confidence interval for the population mean, if the sample size is 58, the sample mean is…

A:

Q: In a survey, 28 people were asked how much they spent on their child's last birthday gift. The…

A:

Q: Suppose a sample of 30 Statistics students are given an IQ test. If the sample has a standard…

A: Given n=30, sample standard deviations s=12.23

Q: A sample of 49 managers reveals a sample mean of $45,420. The standard deviation of the samp is…

A: As the population standard deviation is not known, we will use t-distribution. The number of degrees…

Q: A tire producer wants to test whether the mean diameter of the tires produced on a given day equals…

A: Given Information: Sample size (n) = 48  Mean Diameter (u) = 36.4 inches Standard Deviation (s) =…

Q: The population standard deviation for the height of college hockey players is 3.4 inches. If we want…

A:

Q: Use the formula for a Confidence Interval for Two Proportions to calculate a 95% confidence interval…

A: Confidence interval: The (1-α)100 % confidence interval for proportion p1 – p2 is given by,

Q: A financial institution wishes to estimate the mean balances owed by its credit card customers. The…

A:

Q: In a survey, 18 people were asked how much they spent on their child's last birthday gift. The…

A:

Q: How large a sample should be selected to provide a 95% confidence interval with a margin of error of…

A:

Q: In a survey, 28 people were asked how much they spent on their child's last birthday gift. The…

A: Since population standard deviation is unknown, Use t-distribution to find t-critical value. Find…

Q: In an effort to estimate the mean amount spent per customer for dinner at a major Atlanta…

A: From the provided information, Sample size (n) = 49 Sample mean (x̅) = $24.80 Population standard…

Q: In a survey, 23 people were asked how much they spent on their child's last birthday gift. The…

A:

Q: A random sample of 100 observations produced a mean x̅ =38.5 and a standard deviation of 3.2. find a…

A: Given information Sample size(n) = 100 Sample mean x̅ =38.5 Sample standard deviation = 3.2…

Q: A random variance survey of 495 adults found that 59 had diabetes. which of the following is a 98%…

A:

Q: A student conducted a study and reported that the 95% confidence interval for the population mean…

A:

Q: What is the 90% confidence interval for the variance of exam scores for 28 algebra students, if the…

A: Obtain the 90% confidence interval for the variance of exam scores. The 90% confidence interval for…

Q: In a survey, 19 people were asked how much they spent on their child's last birthday gift. The…

A: From the given information, there are 19 people with the sample mean is $49 and the sample standard…

Q: A study of 64 bolts of carpet showed that their average length was 75 yards. The standard deviation…

A:

Q: An irate student complained that the cost of textbooks was too high. He randomly surveyed 36 other…

A: Given that,x¯=121.60,σ=6.36,n=36 Critical value: By using the z-tables, the critical value at 10%…

Q: Find the margin of error for a​ 95% confidence interval for estimating the population mean when the…

A: Sample S.D = s = 110

Q: Identify the y-score for a 99% confidence interval if the sample size is 35.

A: We have to find critical value for given data..

Q: Suppose our estimate for the mean score for the Player A group was 48 ± 5% SE (standard error). What…

A: Given: Point estimate = 48 Standard error = 5 Confidence level = 95%

Q: What is the difference in the computation of a confidence interval between cases in which you know…

A: Population standard deviation known: When population standard deviation is known, the z-critical…

Q: In a survey, 12 people were asked how much they spent on their child's last birthday gift. The…

A: Since population standard deviation is unknown, Use t-distribution to find t-critical value. Find…

Q: The average weight of 50 randomly selected minivans was 4,200 pounds. The minivan population…

A: Introduction: The 100 (1 – α) % confidence interval for the population mean, μ, when the population…

Q: In a survey, 21 people were asked how much they spent on their child's last birthday gift. The…

A:

Q: State the equation for the 95% confidence interval?

A: The equation for confidence interval can be stated as: Here x̅ is the sample mean, Zα/2 is the…

Q: How large a sample should be used to provide a 95% confidence interval with a margin of error of 4,…

A:

Q: In a survey, 31 people were asked how much they spent on their child's last birthday gift. The…

A:

Q: Identify the y-score for a 95% confidence interval if the sample size is 15.

A: The confidence level is 0.95.

Q: The 95% confidence interval for the mean contains the sample mean with 95% certainty.TrueFalse

A: The confidence interval provides us a different range at different levels of significance. Since,…

Q: In a survey, 23 people were asked how much they spent on their child's last birthday gift. The…

A:

Q: Indentify the t-score for a 95% confidence interval if the sample size is 50 t=

A: Given n=20 CI=95%

Q: .A sample of seven college wrestlers had an average weight of 267 pounds with a sample standard…

A: It is given that sample mean is 267 and the sample standard deviation is 10.

Q: A sample of 256 managers reveals a sample mean of $45,420. The standard deviation of the sample is…

A: Given: A sample of 256 managers has a sample mean of $45,420 and a standard deviation of $2,050.…

Q: What value of z would you use to calculate the 98% confidence interval for a population mean, given…

A:

Q: A sample data set, n = 115, shows human body temperatures with a mean of 99.6ºF. If the standard…

A: Given Data: n=115x¯=99.6σ=0.75   z-value corresponding to 99% Confidence Interval=2.576

Q: In a survey, 19 people were asked how much they spent on their child's last birthday gift. The…

A: The summary of the statistics is, The degree of freedom is, df=n-1   =19-1   =18 Critical value: By…

Q: In a survey, 41 people were asked how much they spent on their child's last birthday gift. The…

A:

Q: A recent study of 25 motorists showed that they spent an average of P750 per week. The standard…

A: Given : s

Q: A study of 390 kindergarten students showed that they have seen on average 4500 hours of television.…

A: Obtain the 95% confidence interval for the mean of all the students. The 95% confidence interval for…

Q: In a survey, 21 people were asked how much they spent on their child's last birthday gift. The…

A: Obtain the margin of error at an 80% confidence level. The margin of error at an 80% confidence…

Q: Suppose that based on a random sample, a 95% confidence interval for the mean hours slept (per day)…

A:

Confidence Intervals

When we calculate intervals in probability and statistics, it can be simply termed as finding out a confidence interval. The confidence interval is usually calculated from the data set which is observed. The value of the parameter that needs to be calculated is present here only.