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IQ scores are normally distributed with a mean of 100 and a standard deviation of 15 if a certain statistician has an IQ of 140 what percent of the population has an IQ less than he does?
About 98% of the population.
What does the sample standard deviation best estimate?
The standard deviation of the population. the standard deviation of the population.
Why is it that only one normal distribution table is needed to find any probability under the normal curve?
Anything that is normally distributed has certain properties. One is that the bulk of scores will be near the mean and the farther from the mean you are, the less common the score. Specifically, about 68% of anything that is normally distributed falls within one standard deviation of the mean. That means that 68% of IQ scores fall between 85 and 115 (the mean being 100 and standard deviation being 15) AND 68% of adult male heights fall between 65 and 75 inches (the mean being 70 and I am estimating a standard deviation of 5). Basically, even though the means and standard deviations change, something that is normally distributed will keep these probabilities (relative to the mean and standard deviation). By standardizing these numbers (changing the mean to 0 and the standard deviation to 1) we can use one table to find the probabilities for anything that is normally distributed.
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.
Can a standard deviation of a sample be equal to a standard deviation of a population?
Yes
What percentage of the normally distributed population lies within the plus or minus one standard deviation of the population mean?
68.2%
True or false a distribution of sample means is normally distributed with a mean equal to the population mean and standard deviation equal to the standard error of the mean?
True.
When the population is normally distributed population standard deviation s is unknown and the sample size is n equals 15 the confidence interval for the population mean s is based on the?
The Z test.
What are the best statistics to use for data that is normally distributed?
The mean and standard deviation. If the data really are normally distributed, all other statistics are redundant.
IQ scores are normally distributed with a mean of 100 and a standard deviation of 15 if a certain statistician has an IQ of 140 what percent of the population has an IQ less than he does?
About 98% of the population.
IQ scores are normally distributed with a mean of 100 and a standard deviation of 15 If a certain statistician has an IQ of 140 what percent of the population has an IQ less than she does?
99.6% for
What does the sample standard deviation best estimate?
The standard deviation of the population. the standard deviation of the population.
A particular fruit's weights are normally distributed, with a mean of 298 grams and a standard deviation of 13 grams.If you pick one fruit at random, what is the probability that it will weigh between 262 grams and 269 grams?
A particular fruit's weights are normally distributed, with a mean of 760 grams and a standard deviation of 15 grams. If you pick one fruit at random, what is the probability that it will weigh between 722 grams and 746 grams-----A particular fruit's weights are normally distributed, with a mean of 567 grams and a standard deviation of 25 grams.
Why is it that only one normal distribution table is needed to find any probability under the normal curve?
Anything that is normally distributed has certain properties. One is that the bulk of scores will be near the mean and the farther from the mean you are, the less common the score. Specifically, about 68% of anything that is normally distributed falls within one standard deviation of the mean. That means that 68% of IQ scores fall between 85 and 115 (the mean being 100 and standard deviation being 15) AND 68% of adult male heights fall between 65 and 75 inches (the mean being 70 and I am estimating a standard deviation of 5). Basically, even though the means and standard deviations change, something that is normally distributed will keep these probabilities (relative to the mean and standard deviation). By standardizing these numbers (changing the mean to 0 and the standard deviation to 1) we can use one table to find the probabilities for anything that is normally distributed.
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.
Can a standard deviation of a sample be equal to a standard deviation of a population?
Yes
Is population standard deviation the same thing as absolute standard deviation?
No.
