I am Completely Confident
The Big T
The Friend Zone? or Rejection?
What's the sample size?????
The Column of Mystery
100
In a survey of 3611 adult Americans 18 years and older, it was found that 542 have used their smartphone to make a purchase. Obtain a point estimate for the population proportion of adult Americans 18 years and older who have used their smartphone to make a purchase.
What is 0.15.
100
Find the t-value such that the area in the right tail is 0.10 with 25 degrees of freedom.
What is 1.316.
100
In 2010, the standard deviation SAT score one the Math test for all students taking the exam was 112. A teacher believes that due to changes to the high school curriculum, the standard deviation of SAT Math scores has increased. Find the null and alternative hypotheses.
What is H0: σ = 112 and H1: σ > 112
100
The standard deviation of the sampling distribution of x̅, is called the ___________ __________ of the mean.
What is standard error.
100
The ______________ ____________ of the sample mean, x̅, is the probability distribution of all possible values of the random variable x̅ computed from a sample size n from a population with mean µ and standard deviation σ.
What is sampling distribution.
200
In a survey of 3611 adult Americans 18 years and older, it was found that 542 have used their smartphone to make a purchase. Construct a 90% confidence interval for the population proportion of adult Americans who have used their smartphone to make a purchase.
What is 0.1403 and 0.1598.
200
Find the t-value such that the area in the right tail is 0.05 with 30 degrees of freedom.
What is 1.697.
200
Suppose that unknown to you, the reality of the following hypotheses are shown below: H0: µ = 20 False. Ha: µ < 20 True. Without knowing this you decide to accept H0. Have you made an error? If so what type of error did you make?
What is type II error.
200
Determine the µ and σx̅ from the given parameters of the population and the sample size. µ = 80, σ = 14, n = 49.
What is µ = 80, σx̅ = 2.
200
A _______ __________ is the value of a statistic that estimates the value of a parameter.
What is point estimate.
300
In a survey of 3611 adult Americans 18 years and older, it was found that 542 have used their smartphone to make a purchase. Interpret the 90% confidence interval of (0.1403, 0.1598) for this survey.
What is "We are 90% confident that the proportion of adult Americans 18 years and older who have used their smartphones to make a purchase is between 0.1403 and 0.1598."
300
Find the t-value such that the area left of the t-value is 0.01 with 30 degrees for freedom.
What is -2.457.
300
Suppose that unknown to you, the reality of the following hypotheses are as shown below: H0: µ = 0.75 True. Ha: µ ≠ 0.75 False. Without knowing this you decide to reject H0 and accept Ha. Have you made an error? If so what type of error have you made?
What is type I error.
300
A simple random sample of size n = 12 is obtained from a population with µ = 64 and σ = 17. Determine the probability of the sample mean being less than 67.3 with a sample of 95 being taken.
What is 0.9708.
300
As the level of confidence of a confidence interval increases, the margin of error ________ (increases/decreases).
What is increases.
400
A 90% confidence interval for the number of hours full-time college students sleep during a weekday is lower bound: 7.8 hours and upper bound: 8.8 hours. Which of the following represents a reasonable interpretation of the result? For those that are not reasonable, explain the flaw. a. 90% of full-time college students sleep between 7.8 hours and 8.8 hours. b. We are 90% confident that the mean number of hours of sleep that full-time college students get any day of the week is between 7.8 hours and 8.8 hours. c. There is a 90% probability that the mean hours of sleep that full-time college students get during a weekday is between 7.8 and 8.8 hours. d. We are 90% confident that the mean hours of sleep that full-time college students get during a weekday is between 7.8 and 8.8 hours.
What is answer D.
400
Find the critical t-value that corresponds to 90% confidence. Assume 42 degrees of freedom.
What is -1.682 and 1.682.
400
1. The weights of newborn baby boys born at a local hospital are normally distributed, with a known standard deviation of 9.5 ounces. A hospital administrator is concerned that the weights of newborn baby boys at the hospital might be less than 110 ounces. The administrator determines that a random sample of size n= 35 had a mean weight of 105 ounces. At α = 0.01 level of significance, do these data indicate that the mean weight of all newborn baby boys born at the local hospital less than 110 ounces? What is the p-value?
What is There is sufficient evidence to support H1, that baby boys at this hospital weigh less than 110 ounces. P-value is equal to 0.0018, so we can reject H0.
400
The reading speed of second grade students is approximately normal, with a mean of 90 words per minute (wpm) and a standard deviation of 10 wpm. What is the probability that a random sample of 24 second grade students results in a mean reading rate of more than 95 words per minute?
What is 0.0071.
400
The ___________ ____________ is a statement we are trying to find evidence to support.
What is alternative hypothesis.
500
A recent Gallup poll asked 1006 Americans, “During the past year, about how many books, either hardcover or paperback, did you read either all or part of the way through?” Results of the survey indicated that x̅ = 13.4 books and s = 16.6 books. Construct a 99% confidence interval for the mean number of books that Americans read either all or part of during the preceding year. Interpret the interval.
What is 12.05 and 14.75. We can be 99% confident that the mean number of books read by Americans in the past year was between 12.05 and 14.75.
500
Find the critical t-value that corresponds to 96% confidence. Assume 57 degrees of freedom.
What is -2.101 and 2.101.
500
2. A study of 500 randomly selected adults in the United States yielded an average of 2400 calories consumed per day, with a standard deviation of 930 calories. Test the claim, which was made prior to the study, that the true mean caloric intake of all adults in the United states is no more than 2300 calories per day, use α = 0.05. What is the p-value?
What is There is sufficient evidence to support H1, that adults in the U.S. intake more than 2300 calories per day. P-value is 0.0083 so yes we can reject H0.
500
The reading speed of second grade students is approximately normal, with a mean of 90 words per minute (wpm) and a standard deviation of 10 wpm. What is the probability that a random sample of 50 second grade students results in a mean reading rate of more than 95 words per minute?
What is 0.0002.
500
What is the central limit theorem?
What is Regardless of the shape of the underlying population, the sampling distribution of x̅ becomes approximately normal as the sample size, n, increases.
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