Sampling distribution

Find the number

z

needed in the construction of a confidence interval:

when the level of confidence is 90%

• 1.64

• 2.58

• 2.33

• 1.96

Find the number

z​​

needed in the construction of a confidence interval:

when the level of confidence is 99%

• 1.64

• 1.96

• 2.33

• 2.58

A sample of size 49 has sample mean 35 and sample standard deviation 11. Construct a 98% confidence interval for the population mean using this information.

• 13.34,38.66

• 38.66,31.34

• 31.34,38.66

• 38.66,13.34

A random sample of 120 students from a large university yields mean GPA 2.71 with sample standard deviation 0.51. Construct a 90% confidence interval for the mean GPA of all students at the university

• 1.63,3.79

• 2.63,2.79

• 3.79,1.63

• 2.97,2.63

Find the minimum sample size necessary to construct a 99% confidence interval for mu with a margin of error E=0.2. Assume that the population standard deviation is sigma=1.3.

• 208

• 280

• 260

• 206

An economist wishes to estimate, with a 95% confidence interval, the yearly income of welders with at least five years experience to within $1,000. He estimates that the range of incomes is no more than $24,000, so using the Empirical Rule he estimates the population standard deviation to be about one-sixth as much, or about $4,000. Find the estimated minimum sample size required.

• 14

• 41

• 16

• 61

A random sample is drawn from a population of known standard deviation 11.3. Construct a 90% confidence interval for the population mean based on the information given (not all of the information given need be used)

n= 100, x¯ = 105.2, s = 11.2

• 103.35,107.05

• 93.35,117.05

• 107.05,103.35

• 117.05,93.35

Emer made a one-sample z interval for a proportion and used the critical value z=1. 476.

What confidence level did she use?

• 84%

• 86%

• 88%

• 92%

Random samples of size 225 are drawn from a population with mean 100 and standard deviation 20. Find the mean and standard deviation of the sample mean

Random samples of size 64 are drawn from a population with mean 32 and standard deviation 20. Find the mean and standard deviation of the sample mean