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How many students of 1800 will have an IQ score above 109 with a mean of 100 and a standard deviation of 15?
Wiki User
∙ 14y ago
You can find this using a table of z scores.
Z = (x - mu) / s
Z = (109 - 100) /15 = 9/15 = 3/5 = .6
You want the percentage of students having a z score above .6.
p = 1 - .7257 = .2743
.2743 * 1800 = 493 students with a score above 109
Wiki User
∙ 14y ago
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Why use the T score?
T-score is used when you don't have the population standard deviation and must use the sample standard deviation as a substitute.
What happens to the standard score as the standard deviation increases?
The absolute value of the standard score becomes smaller.
How many SD below or above the mean would this child's z-score of -2 be?
2 standard deviation's below the mean
Why normality is required for standard deviation application?
Because the z-score table, which is heavily related to standard deviation, is only applicable to normal distributions.
If a test score of 83 was transformed into a standard score of -1.5 and the standard deviation of the scores was 4 what is the mean?
78
How are Stanford-Binet intelligence scale results measured?
.The test has a mean, or average, standard score of 100 and a standard deviation of 16 (subtests have a mean of 50 and a standard deviation of 8). The standard deviation indicates how far above or below the norm the subject's score is.
What happens to the standard score as the standard deviation increase?
The standardised score decreases.
Why use the T score?
T-score is used when you don't have the population standard deviation and must use the sample standard deviation as a substitute.
Which is better a score of 92 on a test with a mean of 71 and a standard deviation of 15 or a score of 688 on a test with a mean of 493 and a standard deviation of 150?
score of 92
How do you calculate standard deviation with the help of z-score?
A z-score cannot help calculate standard deviation. In fact the very point of z-scores is to remove any contribution from the mean or standard deviation.
What happens to the standard score as the standard deviation increases?
The absolute value of the standard score becomes smaller.
When is a t test better than a z score?
When you don't have the population standard deviation, but do have the sample standard deviation. The Z score will be better to do as long as it is possible to do it.
How do you know if a z score is positive or negative?
A negative Z-Score corresponds to a negative standard deviation, i.e. an observation that is less than the mean, when the standard deviation is normalized so that the standard deviation is zero when the mean is zero.
Scores on an exam are normally distributed with a mean of 76 and a standard deviation of 10 In a group of 230 tests how many students score below 66?
There are approximately 16.4% of students who score below 66 on the exam.
A z score is most affected by?
standard deviation
Can The standard deviation of a distribution be a negative value?
No. The standard deviation is not exactly a value but rather how far a score deviates from the mean.
How many SD below or above the mean would this child's z-score of -2 be?
2 standard deviation's below the mean
