Confidence Interval; Sampling Distribution; Mean and Standard Deviation

1. A parcel service randomly selected 48 packages it received. The sample has a mean weight of 18.6 pounds. Assume that σ = 3.4 pounds. Construct a 90% confidence interval for the true mean weight, μ, of all packages received by the parcel service.

2. A phone company wants to estimate the mean duration of local calls. Assume σ = 3.0. the sample size is 540. Find the margin of error in estimating μ at the 90% level of confidence.

3. The mean and standard deviation for a population are 107 and 14, respectively. Samples of size 49 are selected randomly from the population. Find the mean and standard deviation of the sampling distribution.

4. The weekly earnings of students in one age group are approximately normally distributed with a standard deviation of 36 dollars. A researcher wishes to estimate the mean weekly earnings. Find the sample size needed if she requires a 90% degree of confidence that the sample mean will not differ from the population by more than 3 dollars.

5. A sample of cereal boxes were selected, and their weights in ounces were recorded in the attachment. Determine a 95% confidence interval for the mean weight of cereal in all boxes.

Please see the attachment for correct formatting and complete information.

1.Which of the following statements about the sampling distribution of the sample mean is incorrect?
a. The sampling distribution of the sample mean is approximately normal whenever the sample size is sufficiently large (n>30).
b. The sampling distribution of the sample mean is generated by repeatedly taking samples of size n

Please choose the correct answers and state briefly why:
In a manufacturing process a random sample of 36 bolts manufactured has a mean length of 3 inches with a standard deviation of .3 inches. What is the 99% confidence interval for the true mean length of the bolt?
a. 2.902 to 3.098
b. 2.884 to 3.117
c. 2.87

1) The distribution of sample mean for samples of 500 homes is normal with a mean of 2.64 and a standard deviation of 0.06. Suppose you select a random sample of n=500 homes and determine that the mean number of people per home for this sample id 2.55. How many standard deviations is the sample mean of the sampling distribution?

In a manufacturing process a machine produces bolts that have an average length of 3 inches with a variance of .03. If we randomly select three bolts from this process: What is the standard deviation of the sampling distribution of the sample mean?

Q1
You are a proprieter of NYC boutique. You want to know the average age of your customers. You take a random sample of 25 customers which yields an average age of 32 yrs with a standard deviation of 8. You have reason to belive the distibution of ages is normally distributed. Determine a 95% confidence interval for the age

Suppose a population consisted of 20 items. How many different samples of n = 3 are possible?
A. 1140
B. 6840
C. 20
D. 120
The difference between the sample meanand the population mean is called the
A. Population standard deviation.
B. Population mean.
C. Standard error of the mean.
D. Sa

Which of the following is true about the sampling distribution of the sample mean?
A. The mean of the sampling distribution is always "u"
B. The standard deviation of the sampling distribution is always "o"
C. The shape of the sampling distribution is always approximately normal
D. All of the above

The grade point averages for 10 randomly selected students are listed in column 1 of the minitab worksheet. the distribution of GPAs is known to be approximately normally distributed.
If possible, construct a 90% confidence interval for the population standard deviation. Interpret the meaning of the interval.
GPAs
2.0

Suppose Stat I students ages follow a skewed right distribution with a mean of 24 years old and a standard deviation of 2 years old. If we randomly sampled 150 students, which of the following statements about the sampling distribution of the sample mean age is incorrect?
-The mean of the sampling distribution is approximate

Use the given degree of confidenceand sample data to find a confidence interval for the population standard deviation o. Assume that the population has a normal distribution.
Weights of men: 90% confidence; n=14, Xbar=160.9lb, s=12.6lb