Ch.7 Quiz (Possible questions and actual quiz)

A sample of n= 4 scores has a standard error of 12. What is the standard deviation of the population from which the sample was obtained?

24 12 * sqrt 4= 24

A random sample of n= 4 scores is obtained from a normal population with mean=40 and standard deviation=6. What is the probability of obtaining a mean greater than M=46 for this sample?

0.0228 use om=o/sqrt n and then z= M-u/om use s score chart and look at c section of 2.00

A random sample of n=4 scores is obtained from a normal population with mean=20 and standard deviation =4. What is the probability of obtaining a mean greater than M= 22 for this sample?

0.1587 use om=o/sqrt n and then z= M-u/om use s score chart and look at c section of 1.00

For a population with a mean of μ = 40 and a standard deviation of 𝜎=8, find the z-score corresponding to a sample mean of 𝑋= 44. What is the z-score for the sample of n = 16?

2 Since you are focusing on a group of 16 people, you need to need to find the standard error = 2 first. Z = (44-40)/2= 2

Samples of size n = 9 are selected from a population with μ = 80 with σ = 18. What is the standard error for the distribution of sample means?​

6 The standard error is σ/sqrt n.

If random samples, each with n= 9 scores, are selected from a normal population with mean= 80 and standard deviation= 18, and the mean is calculated for each sample, then how much distance is expected on average between M and M and Mm?

6 points 18/sqrt9 = 6

If all possible random samples, each with n=9 scores, are selected from a normal population with mean= 80 and standard deviation =18, and the mean is calculated for each sample, then what is the average for all of the sample means?

80 little mean = big mean

If random samples, each with n=5 4 scores, are selected from a normal population with m= 80 and s= 10, then what is the expected value of the mean for the distribution of sample means?

80 m= big M

For a population with µ = 80 and σ = 20, the distribution of sample means based on n = 16 will have the mean of the sample means____ and a standard error of ____.​

80; 5 Standard error is σ/sqrt n. The mean of the sample means is always the same as the population mean.

If all possible random samples of size n=25 are selected from a population with mean= 80 and standard deviation =10 and the mean is computed for each sample, then what shape is expected for the distribution of sample means?

The sample means tend to form a normal-shaped distribution.

All the possible random samples of size n=2 are selected from a population with mean=40 and standard deviation =10 and the mean is computed for each sample. Then all the possible samples of size n=25 are selected from the same population and the mean is computed for each sample. How will the distribution of sample means for n=2 compare with the distribution for n= 25?

The variance for n=25 will be smaller than the variance for n=2 but the two distributions will have the same mean.

When the sample size changed from 4 to 30, the standard error decreases.

True The standard error is σ/sqrt n. If n becomes large, the standard error gets smaller.

What is the probability of obtaining a sample mean greater than 𝑋 X= 60 for a random sample of n = 16 scores selected from a normal population with a mean of μ = 65 and a standard deviation of 𝜎= σ=20?

p = .8413 The standard error is 5, Z = -1. The area you highlight should be on the right-hand side. The body.

A sample of n= 16 scores is obtained from a population with mean= 70 and standard deviation=20. If the sample mean is M=75, then what is the z-score corresponding to the sample mean?

z=1.00 use standard deviation mean formula om=0/srqrt n then use z score formula z=m-u/om