Exam 2
false
A sample of n=25 scores is selected from a population with a mean of m=80and a standard deviation o=20. The standard error for the sample mean is 20
Mary, Sue , Bob
For an exam with a mean of m=74 and a standard deviation of s=8, Mary has a score of X=80, Bob's score corresponds to z=+1.50, and Sue score is located above the mean by 10 points. If the students are placed in order from SMALLEST to LARGEST score what is the correct order?
false
If the sample size is doubled, the standard error will be cut in half
false
The probability of randomly selecting a red marble from a jar that contains 10 marbles and 20 blue marbles is 1/30
true
The proportion in the body of a normal distribution can never be less than .50
.7888
What proportion of a normal distribution is located between z=-1.25 and z=+1.25
proportions in both tails are positive
Which of following accurately describes the proportions in the tails of a normal distribution?
x=55
a distribution with m=55 and o =6 is being standardized so that they new mean and standard deviation will be m=50 and o=10 when the distribution is standardized, what value will be obtained for a score of x=58 from the original distribution
false
a population has a m=60 and o=30 for a sample of n=25 scores from this population, a sample mean of M=55 would be considered an extreme value
false
a population with m=41 and o=4 is standardized to create a new distribution with m=50 and o=10. in this transformation, a score of x=39 from the original distribution will be transformed into a score of x=55
true
a professor standardizes exam scores so that all the exams have m=50 and o=10. if the original scores from an exam have m=42 and o=6 , then a student with an original exam score of x=45 would receive a standardized score of x=55
p(402)<m<598)=0.95
a random sample of n=16 scores is selected from a normal distribution with m=500 and o=200 . For this sample which of the following is true ?
true
a sample is selected from a population m=30 and o=10. if the sample mean of m=34 corresponds to z=+2.00, then the sample size is n=25
false
a sample of n=25 scores is selected from a population with m= 50 and o=10. the probability of obtaining a sample mean GREATER than 55 is p=.3085
false
a sample of n=9 scores is selected from a population with a m=40 and o=18. if the sample mean corresponds to z=-1.00 then the sample mean is m=31
true
a vertical line is drawn thru a normal distribution so that 47.5% of the distribution is located between the line and the mean the line is drawn at z=1.96 or at z=-1.96
true
according to the central limit theorem, the standard error for a sample mean becomes smaller as the sample size increases
false
for a normal distribution, the proportion in the tail beyond z=-2.00 is equal to -.0228
false
for a population with m=34 , a score of x=31 corresponds to z=-1.00. the standard deviation for the population is o=6
false
for a sample with m=50 and s=8, z=1.50 corresponds to x=65
true
for any distribution of scores, the location identified by z=+1and the location identified as z=-1are exactly the same distance from the mean
false
if one score is randomly selected from a normal distribution with m=100 and o=20, the probability of obtaining a score between x=80 and x=120 is p=0.3413
false
if the sample size is equal to the population standard deviation (n=o), then the standard error for the sample mean is equal to 1.00
m=85 o=4
in a population of scores x=83 corresponds to z=-.50 and x=93 corresponds to z=+2.00 what are the values for the population mean and standard deviation
m=48
in a population with o=8, a score of x=44 corresponds to a score of .50 what is the population mean?
.2743
john drives to work each morning, and the trip takes an average of m=38 minutes . the distribution of driving times is approximately normal with a standard deviation of o= 5 minutes. for a randomly selected morning, what is the probability that johns drive to work will take LESS than 35 minutes
o=2
on an exam with m=52, you have a score of x=56. Which value for the standard deviation would give you the highest position in the class distribution ?
false
on average, a sample of n=16 scores from a population with o=10 will provide a better estimate of the population mean than you would get with a sample of n=16 scores with a population with o=5
m=40 o=8
samples of n=16 scores are selected from a population. If the distribution of sample means has an expected value pf 40 and a standard error of 2, what are the mean and the standard deviation for the population?
false
the mean for a sample of n=9 scores has a standard error of 2 points this sample was selected from a population with a standard deviation of o=18
true
the mean for the distribution of sample means is always equal to the mean for the population from which samples are obtained
true
two samples probably will have different means even if they are both the same size and they are both selected from the same population
z=-0.52
what z score value separates the highest 70% of the scores in a normal distribution from the lowest 30%?
m=60 o=5
you have a score of x=65 on an exam. which set of parameters would give you the best grade on the exam?