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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
What happens to the standard score as the standard deviation increase?
The standardised score decreases.
Is 119 an average id score for a 7 year old?
An average IQ score for a 7 year old is typically around 100, so a score of 119 would be considered above average. IQ scores are standardized to have a mean of 100 with a standard deviation of 15, so a score of 119 would fall about 1 standard deviation above the average.
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
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 does the standard deviation get smaller as the individual in a group score more similarly on a test?
Because the standard deviation is a measure of the spread in scores. As individuals score more similarly, the spread gets smaller. Because the standard deviation is a measure of the spread in scores. As individuals score more similarly, the spread gets smaller. Because the standard deviation is a measure of the spread in scores. As individuals score more similarly, the spread gets smaller. Because the standard deviation is a measure of the spread in scores. As individuals score more similarly, the spread gets smaller.
