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It depends on the significance level required. And that, in turn, will depend on the cost of making the wrong decision. For ordinary use, a 95% significance level will require 1.96 sd

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If average height for women is normally distributed with a mean of 65 inches and a standard deviation of 2.5 inches then approximately 95 percent of all women should be between what and what inches?

A normal distribution with a mean of 65 and a standard deviation of 2.5 would have 95% of the population being between 60 and 70, i.e. +/- two standard deviations.


When computing Standard deviation should you eliminate the extreme values?

Generally not without further reason. Extreme values are often called outliers. Eliminating unusually high values will lower the standard deviation. You may want to calculate standard deviations with and without the extreme values to identify their impact on calculations. See related link for additional discussion.


How do you solve this problem. You drive to work. Drive time mean 30 min standard deviation 4 min. Workday begins at 9am. What time should you leave so that probability on time is 95 percent?

if standard deviation is 4 minutes 95% probability is about 2 standard deviations (actually 1.96) so you would need to allow 30 + 8 = 38 minutes


How many outliers can a data set have?

There is no agreed definition of an outlier and consequently, there is no simple answer to the question. The number of outliers will depend on the criterion used to identify them. If you have observations from a normal distribution, you should expect around 1 in 22 observations to be more than 2 standard deviations from the mean, and about 1 in 370 more than 3 sd away. You will have more outliers if the distribution is non-normal - particularly if it is skewed.


How intelligent is an IQ of 145?

It depends on what the standard deviation for that particular scale is. The most well-known scales have standard deviations of 15. In that case, 145 is three standard deviations above the average. People with this score are considered borderline geniuses. You can expect a well-educated student who has this IQ to be about six, maybe seven years ahead of his classmates. Someone with this IQ is incredibly intelligent and creative. Creativity, in this sense, is not artistic talent. It is the ability to solve logical problems using previously unknown methods. For example, someone who creates a new way to solve sudoku problems is intelligent, not someone who learns how to use them. One in 741 people reach the fourth standard deviation (an IQ of 145 or above in this case). IQ does not measure academic skill. It measures academic potential. The IQ test on tickle.com should be thought of as an aptitude test. Tests that measure actual IQ have questions similar to those on iqtest.dk. Even the WISC and WAIS IQ tests have questions which should only be put in aptitude tests. Remember that no matter which test it is, an online test is invalid. Even if it's a well made, properly calibrated test, your surroundings can affect your score.

Related Questions

How do you multiply standard deviations?

Multiply them as you would any two numbers. However, you should note that the standard deviation of a product of two variables is not the product of their standard deviations. That is, SD(XY) ≠ SD(X)*SD(Y)


What is the measures that fall beyond three standard deviations of the mean called?

You may be referring to the statistical term 'outlier(s)'. Also, there is a rule in statistics called the '68-95-99 Rule'. It states that in a normally distributed dataset approximately 68% of the observations will be within plus/minus one standard deviation of the mean, 95% within plus/minus two standard deviations, and 99% within plus/minus three standard deviations. So if your data follow the classic bell-shaped curve, roughly 1% of the measures should fall beyond three standard deviations of the mean.


Is standard deviation the arithmetic mean of the squared deviations from the means?

No. Standard deviation is the square root of the mean of the squared deviations from the mean. Also, if the mean of the data is determined by the same process as the deviation from the mean, then you loose one degree of freedom, and the divisor in the calculation should be N-1, instead of just N.


If average height for women is normally distributed with a mean of 65 inches and a standard deviation of 2.5 inches then approximately 95 percent of all women should be between what and what inches?

A normal distribution with a mean of 65 and a standard deviation of 2.5 would have 95% of the population being between 60 and 70, i.e. +/- two standard deviations.


When computing Standard deviation should you eliminate the extreme values?

Generally not without further reason. Extreme values are often called outliers. Eliminating unusually high values will lower the standard deviation. You may want to calculate standard deviations with and without the extreme values to identify their impact on calculations. See related link for additional discussion.


What is standard quantity?

Standard quantity refers to the planned or expected amount of material, labor, or overhead that should be consumed or used in producing a product or providing a service. It serves as a benchmark for evaluating the actual usage and efficiency of resources in production processes. Variance analysis compares actual quantities used with standard quantities to identify deviations and improve cost control.


How do you solve this problem. You drive to work. Drive time mean 30 min standard deviation 4 min. Workday begins at 9am. What time should you leave so that probability on time is 95 percent?

if standard deviation is 4 minutes 95% probability is about 2 standard deviations (actually 1.96) so you would need to allow 30 + 8 = 38 minutes


What two kinds of time did Sir Sandford Fleming want to establish?

He proposed in 1879 that there should be Universal Standard Time covering the whole world linked back to the time at Greenwich.


Can the non custodial father file for a child support order for himself?

Yes. A non-custodial parent can file a petition to establish his parental rights. He can petition to establish his paternity, to establish custody and visitation and to establish a child support order. He should visit the court and ask to speak with an advocate in the family court. If possible he should consult with an attorney.Yes. A non-custodial parent can file a petition to establish his parental rights. He can petition to establish his paternity, to establish custody and visitation and to establish a child support order. He should visit the court and ask to speak with an advocate in the family court. If possible he should consult with an attorney.Yes. A non-custodial parent can file a petition to establish his parental rights. He can petition to establish his paternity, to establish custody and visitation and to establish a child support order. He should visit the court and ask to speak with an advocate in the family court. If possible he should consult with an attorney.Yes. A non-custodial parent can file a petition to establish his parental rights. He can petition to establish his paternity, to establish custody and visitation and to establish a child support order. He should visit the court and ask to speak with an advocate in the family court. If possible he should consult with an attorney.


Describe the properties of a normal distribution?

A normal distribution is symmetric and when looked at on a graph, the graph looks like a bell shaped curve. Approximately 95 percent of its values should lie within two standard deviations of the mean. Frequency of the data lies mostly in the middle of the curve.


In which direction should a headstone face for proper placement and significance?

A headstone should typically face east for proper placement and significance.


In which direction should the temple face for optimal alignment and significance?

The temple should ideally face east for optimal alignment and significance.