Unit 3 Flashcards
In a normal curve, the inflection points occur at ____.
Μ ± 1σ
Given below are lower and upper limits of areas of the normal curve. Choose the limits that mark off the greatest proportion of the normal curve.
-lσ to 1σ
Given below are lower and upper limits of areas of the normal curve. Choose the limits that mark off the greatest proportion of the normal curve.
-lσ to 0
You have just received your psychology exam grade and you did better than the mean of the exam scores. If so, the z transformed value of your grade must
must be greater than 0.00 and
have a percentile rank greater than 50%
Associated with a point of inflection on a normal curve is
one standard deviation
A testing service has 1000 raw scores. It wants to transform the distribution so that the mean = 10 and the standard deviation = 1. To do so, ____.
Do a z transformation for each raw score and add 10 to each z score. and
Divide each deviation score by the standard deviation of the raw scores. Take this result for all scores and add 10 to each one.
Would you rather have an income (assume a normal distribution and you are greedy) ____.
with a z score of 1.96
Another name for a z score is
standard score
Under what circumstances would a score that is 15 points above the mean be considered to be near the center of the distribution?
when the population standard deviation is much larger than 15
Approximately what percentage of scores fall between z = 1 and z = 1.5?
9%
A population of scores has = 42. In this population, an X value of 40 corresponds to z = 0.50. What is the population standard deviation?
4
Data Set 4-3: -2, -1, 0, 2, 6
A raw score of -2 in Data Set 4-3 has a z score of
-1.06
Data Set 4-4: 2, 4, 6, 8
For the population Data Set 4-4 a raw score of 6 has a z score of
0.45
Data Set 4-1: 2, 7, 3, 6, 2
For population Data Set 4-1 a raw score of 7 has a z score of
1.43
Approximately what percentage of scores fall between z = 0 and z = .5?
19%
A population of scores has = 20. In this population, a score of X = 80 corresponds to z = +0.25. What is the population mean?
75
Data Set 4-3: -2, -1, 0, 2, 6
A raw score of 6 in the population Data Set 4-3 has a deviation score of
5
For any normal distribution, what is the probability of selecting a score less than the mean?
50%
Suppose that Graduate Record Examination (GRE) scores are normally distributed with a mean Μ = 500 and standard deviation σ = 100. What is the z score that corresponds to a GRE score of 600?
1
Let’s assume that the scores are normally distributed on a test with a population mean of 75 and standard deviation equal to 16. What is the percentile rank of a score of 56?
11.7
Suppose that Graduate Record Examination (GRE) scores are normally distributed with a mean Μ = 500 and standard deviation σ = 100. What is the z score that corresponds to a GRE score of 350?
-1.5
The advantage of using z scores over using raw scores is that z scores allow you to
compare a score in one distribution to a score in another and
understand the relationship of a score to the mean
A z-score of z = +3.00 indicates a location that is __________.
far above the mean in the extreme right-hand tail of the distribution
The theoretical normal distribution has
parameters
What two parameters of a population must be known in order to use the normal curve table?
mean and standard deviation
Which of the following is a characteristic of a normal distribution?
symmetric, unimodal, asymptotic
The standard normal distribution is a ____ distribution with μ = ____ and σ = ____.
normal, 0, 1
The theoretical normal curve has a mean equal to __________ and a standard deviation equal to __________.
0, 1
What proportion of the scores in a normal distribution fall below z = –1.32?
0.0934
What proportion of a normal distribution is located in the tail beyond a z-score of z = 1.50?
0.0668
For a normal distribution with mean of 75 and standard deviation of 25, the proportion of the scores between 90 and 100 is
.1156
A testing bureau reports that the mean for the population of Graduate Record Exam (GRE) scores is 500 with a standard deviation of 90. The proportion of scores that lie above 650 is ____.
0.0475
Scores on the Math Achievement Test form a normal distribution with a mean of = 300 and a standard deviation of = 100. What score separates the top 10% of the distribution from the rest?
428
A stockbroker has kept a daily record of the value of a particular stock over the years and finds that prices of the stock form a normal distribution with a mean of $8.52 with a standard deviation of $2.38. The percentage of scores that lie between $9.00 and $10.00 is ____.
15.31%
SAT scores form a normal distribution with a mean of = 500 and a standard deviation of = 100. The probability of randomly selecting an SAT score greater than 450 is __________.
0.6915
A normal distribution has a mean of = 60 with = 8. What is the probability of selecting an individual with a score greater than 54?
0.7734
A very bright student is described as having an IQ that is three standard deviations above the mean. If this student’s IQ is reported as a z-score, the z-score would be
3
