The

UkusakazaL
2021-08-09
Answered

The scores of a certain population on the Wechsler Intelligence Scale for children (WISC) are thought to be normally distributed with a mean and standard deviation of 10. A simple random sample of twenty -five children from this population is taken and each is given the WISC. The mean of the twenty-five score is $\stackrel{\u2015}{x}=104.32$ . Based on these data a $95\mathrm{\%}$ confidence interval for $\mu$ is computed.

The$95\mathrm{\%}$ confidence interval for $\mu$ is?

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Answered 2021-08-16
Author has **155** answers

Step 1

Given:

Step 2

The

From the Z table

Answer:

asked 2020-12-27

Consider the next 1000 98% Cis for mu that a statistical consultant will obtain for various clients. Suppose the data sets on which the intervals are based are selected independently of one another. How many of these 1000 intervals do you expect to capture the corresponding value of $\mu ?$

What isthe probability that between 970 and 990 of these intervals conta the corresponding value of ? (Hint: Let

Round your answer to four decimal places.)

‘the number among the 1000 intervals that contain What king of random variable s 2) (Use the normal approximation to the binomial distribution

What isthe probability that between 970 and 990 of these intervals conta the corresponding value of ? (Hint: Let

Round your answer to four decimal places.)

‘the number among the 1000 intervals that contain What king of random variable s 2) (Use the normal approximation to the binomial distribution

asked 2021-08-04

A random sample of 100 automobile owners in the state of Virginia shows that an automobile is driven on average 23,500 kilometers per year with a standard deviation of 3900 kilometers.

Assume the distribution of measurements to be approximately normal.

a) Construct a$99\mathrm{\%}$ confidence interval for the average number of kilometers an automobile is driven annually in Virginia.

b) What can we assert with$99\mathrm{\%}$ confidence about the possible size of our error if we estimate the average number of kilometers driven by car owners in Virginia to be 23,500 kilometers per year?

Assume the distribution of measurements to be approximately normal.

a) Construct a

b) What can we assert with

asked 2021-02-23

Suppose that a random sample of 50 bottles of a particular brand of cough syrup is selected and the alcohol content of each bottle is determined. Let j: denote the average alcohol content for the population of all bottles of the brand under study. Suppose that the resulting 95% confidence intervals (7-8, 9.6)

(a) Would 2 90%% confidence interval calculated from this same sample have been narrower or wider than the glven interval? Explain your reasoning.

(b) Consider the following statement: There is 9 95% chance that Is between 7.8 and 9.6. Is this statement correct? Why or why not?

(c) Consider the following statement: We can be highly confident that 95% of al bottles ofthis type of cough syrup have an alcohol content that is between 7.8 and 9.6. Is this statement correct? Why or why not?

(a) Would 2 90%% confidence interval calculated from this same sample have been narrower or wider than the glven interval? Explain your reasoning.

(b) Consider the following statement: There is 9 95% chance that Is between 7.8 and 9.6. Is this statement correct? Why or why not?

(c) Consider the following statement: We can be highly confident that 95% of al bottles ofthis type of cough syrup have an alcohol content that is between 7.8 and 9.6. Is this statement correct? Why or why not?

asked 2021-01-10

The average zinc concentration recovered from a sample of measurements taken in 36 different locations in a river is found to be 2.6 grams per liter. Find the 95% confidence intervals for the mean zinc concentration in the river. Assume that the population standard deviation is 0.3 gram per liter.

asked 2021-02-09

The service life in kilometer of Goody tires is assumed to follow a normal distribution with a standard deviation of 5,000 km. A random sample of 25 tires yielded a mean service life of 30,000 km.
1) Find the $95\mathrm{\%}$ confidence interval for the true mean service life.
2) 2. Find a $75\mathrm{\%}$ confidence interval for the true mean service life.
3) Calculate the widths of the intervals found in 1 and 2. How do these widths change as the
confidence level decreases?

asked 2021-08-03

Find the critical value z a/2 that corresponds to a $93\mathrm{\%}$ confidence level

asked 2022-03-25

Confidence Intervals, Proportion Estimations

In a study of perception, 107 men are tested and 24 are found to have red/green color blindness.

(a) Find a 92% confidence interval for the true proportion of men from the sampled population that have this type of color blindness.

(b) Using the results from the above mentioned survey, how many men should be sampled to estimate the true proportion of men with this type of color blindness to within 2% with 98% confidence?

(c) If no previous estimate of the sample proportion is available, how large of a sample should be used in (b)?

I have already answered (a). However, I am at a complete loss as to how to answer (b) or (c). For one thing, I am not quite sure what (b) is even asking. Advice on this question would be greatly appreciated.

In a study of perception, 107 men are tested and 24 are found to have red/green color blindness.

(a) Find a 92% confidence interval for the true proportion of men from the sampled population that have this type of color blindness.

(b) Using the results from the above mentioned survey, how many men should be sampled to estimate the true proportion of men with this type of color blindness to within 2% with 98% confidence?

(c) If no previous estimate of the sample proportion is available, how large of a sample should be used in (b)?

I have already answered (a). However, I am at a complete loss as to how to answer (b) or (c). For one thing, I am not quite sure what (b) is even asking. Advice on this question would be greatly appreciated.