Question 775803: dear sir,i want answers of these 21 problems..please help me reply me in my email with the answers.
Please check units of measurements in the answers, so that you don't run into trouble with autograding. If you are asked to provide the answer as a percent, and your answer is 90%, please enter 90 but not 90%, nor 0.9, nor 9/10, etc.
Please use the 5% cutoff for P-values unless otherwise instructed in the problem.
A statistician analyzing a randomized controlled experiment has tested Null: The treatment does nothing. Alternative: The treatment does something. using a 4% cutoff for P-values. The P-value of the test turns out to be about 1.8%.
Problem 3 (1 point possible)
First, I will use a simple decision rule: if fewer than half the tosses are heads, I will choose p=0.3; if more than half the tosses are heads, I will choose p=0.6.
The significance level of this test is ____________%.
unanswered
Problem 4 (1 point possible)
The power of the test in Problem 3 is ____________%.
unanswered
Problem 5 (1 point possible)
Suppose I want to create a new decision rule that says, “If the number of heads is less than H, then I will choose p=0.3; otherwise I will choose p=0.6.” Here H is an integer in the range 0 through 15. Is it possible for me to choose H so that the new test has a smaller significance level as well as a higher power than the test in Problem 3? Maybe; there is not enough information to decide. Yes. No.
In a simple random sample of 400 households taken in a large city, 57% of the households contain exactly two people in them; these are called “two-person” households. Construct an approximate 85% confidence interval for the percent of two-person households in the city, and provide the endpoints of the intervals in Problems 6-7. Problem 8 continues the analysis of this sample.
Problem 6 (2 points possible)
The left endpoint of the interval is about __________%.
unanswered
Problem 7 (2 points possible)
The right endpoint of the interval is about __________%.
unanswered
Problem 8 (3 points possible)
Another statistician uses the same sample to construct a confidence interval for the percent of two-person households in the city. The interval goes from 52.5% to 61.5%.
The confidence level of this interval is about ________ %.
unanswered
In a population of over 15,000 patients, the distribution of systolic blood pressure follows the normal curve. Investigators believe the average systolic blood pressure in the population is 120 mm. The investigators take a simple random sample of 6 patients from this population. The systolic blood pressure measurements of these patients have an average of 113.5 mm and an SD (computed with 6 in the denominator) of 12.2 mm. Is the average systolic blood pressure in the population lower than the investigators think? Or is this just chance variation? Answer following the steps in
Problems 9-13.
Problem 9 (0/1.0 points)
The null hypothesis is: The average blood pressure in the population is 120 mm. Status: correct The average blood pressure in the population is less than 120 mm. The average blood pressure in the population is not equal to 120 mm.
Problem 10 (2 points possible)
The approximate distribution of the test statistic is (pick the best option) binomial Status: incorrect hypergeometric normal t chi-square
Problem 11 (1 point possible)
The test is one-tailed two-tailed ?
Problem 12 (3 points possible)
The P-value of the test is approximately _______%
unanswered
Problem 13 (1 point possible)
“The test supports what the investigators think.”
The quoted statement is True False ?
A simple random sample of 1000 freshmen is taken from among freshmen at all private universities in a state. On average, the sampled freshmen worked for 9.2 hours in the week before the survey, with an SD of 9.9 hours. [Here "worked" means "worked for pay".]
Problem 14 (1 point possible)
The interval “8.6 hours to 9.8 hours” is an approximate 95% confidence interval for the average number of hours worked in the week before the survey by freshmen in the sample. at all private universities in the state.
Problem 15 (2 points possible)
In the week before the survey, about 2.5% of the freshmen in the sample worked more than _______hours. Pick the best option. 29 9.8 NA (that is, unknown based on the given information)
Problem 16 (2 points possible)
Because the sample size is large, the Central Limit Theorem says that the _________ is roughly normal. Fill in the blank with the best option. histogram of hours worked in the week before the survey by the sampled freshmen histogram of hours worked in the week before the survey by freshmen at all private universities in the state. probability histogram of the average number of hours worked in the week before the survey by a simple random sample of 1000 freshmen taken from private universities in the state probability histogram of the average number of hours worked in the week before the survey by freshmen at all private universities in the state
A statistician believes that in her town each child born has a 50% chance of being a girl, independently of all other children. There are 281 three-child families in her town; 39 of these families have no girls, 94 have one girl, 115 have two girls, and the remaining 33 have three girls.
Say whether the data support the statistician’s belief, by following the steps in Problems 17-22.
Problem 17 (2 points possible)
If the statistician’s belief is correct, the probability that a three-child family in the town will have exactly one girl is ______%.
unanswered
Problem 18 (1 point possible)
If the statistician’s belief is correct, then among the three-child families in the town what is the expected number of families that have exactly one girl?
unanswered
Problem 19 (2 points possible)
If the statistician’s belief is correct, then among the three-child families in the town what is the expected number of families that have no girls?
unanswered
Problem 20 (1 point possible)
To test whether the data support the statistician’s belief, the appropriate test statistic to use roughly follows a ___________ distribution. normal t chi-square
Problem 21 (3 points possible)
The P-value of the appropriate test is about ________%.
unanswered
Problem 22
The conclusion of the test is that the data support the statistician’s belief. Status: correct do not support the statistician’s belief. You have used 1 of 1 submissions
One year, a simple random sample of 1,000 U.S. 10-year-olds was taken. The children were studied for the entire year. At the beginning of the year the sampled children had an average weight of 70 pounds with an SD of 15 pounds. At the end of the year their weights averaged 75 pounds and the SD was 14.5 pounds. The correlation between their weights at beginning and end of the year was 0.8.
Problem 23 (2 points possible)
An approximate 90% confidence interval for the year-end weight of U.S. 10-year-olds that year is 75 pounds plus or minus about _______ pounds. Fill in the blank with the best of the options below. NA (this blank cannot be filled in with the information given) 0.45 0.75 0.9 24 28
Problem 24 (3 points possible)
Define the weight gain of a child to be “end of year weight - beginning of year weight”. The gain is negative if the child weighs less at the end of the year than at the beginning.
An approximate 95% confidence interval for the average weight gain of U.S. 10-year-olds that year is 5 pounds plus or minus about ________ pounds. Fill in the blank with the best of the options below. NA (this blank cannot be filled in with the information given) 0.15 0.3 0.6 9 18 21
Found 3 solutions by sofiyac, MathTherapy, JamesButler:
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