How to find percentages given a mean and standard deviation?
Here's the skinny: the shape of a bell curve distribution is described by its mean and its standard deviation. To know the probability of a range of values, you need to know the area beneath that curve between the values of interest. There is no formula that spits this out, so you have to look it up in a table. The basic rules of thumb are the following: http://upload.wikimedia.org/wikipedia/co... A) Note that (178-154)/8 is exactly 3. That's not a coincidence. So in the picture, the mean is 178, the middle, and each standard deviation is labeled. So add em up between the values of interest, 154 and 202, which is three standard deviations below the mean and 3 above it. That's 2.1+13.6 + 34.1% + 34.1 + 13.6 + 2.1% =99.6%. B) 170 is one standard deviation (8) below the mean (178) and 186 is two above. That's the region between -one to two standard deviations in the picture or 34 + 34 + 13%.
How to calculate mean given standard deviation and percentage considered?
The income of junior executives in a large corporation are normally distributed with a standard deviation of $1700. A cutback is pending, at which time those who earn less than $28,000 will be discharged. If such a cut represents 30% of the junior executives, what is the current mean (average) salary of the group of junior executives?
Find Standard Deviation Given Percent and Mean?
The distribution of scores on a test is mound-shaped and symmetric with a mean score of 78. If 68% of the scores fall between 72 and 84, which of the following is most likely to be the standard deviation of the distribution? A. 3 B. 12 C 2 D. 6 How can I solve this only using the empirical rule and without having to use a z table of values. Thanks !
Given: Standard deviation of 11.4 and a mean of 40.0. Find the percentage less than 25 times.Please help!?
Okay, the original question is this: A banker studying customer needs finds that the number of times people use automated-teller machines in a year are normally distributed with a mean of 40.0 and a standard deviation of 11.4 Find the percentage of customers who use them less than 25 times.
Calculate percentage when given standard deviation and mean.?
68% of data will be within 1 standard deviation of the mean so since 2.30 + 0.10 = 2.40 and 2.30 - 0.10 = 2.20, part a is asking for within 1 SD of the mean. So 68% 95% will be within 2 SD's of the mean, which would be 47.5% on either side. So since 2.50 = 2.30 + 2 x 0.10, you have 47.5% on that side of the mean, but on the other side is just 1 SD so half of 68% = 34%. Add 47.5% + 34% getting 81.5% Then more than $2.50 is more than 47.5% above the mean, which is at 50%, so 47.5% + 50% = 97.5% leaving only 2.5% above 2 SD's.
Statistics: Given the mean and standard deviation; find some percents?
I am having a hard time with my statistics problem: Middle-aged men are more susceptible to high cholesterol than the young women of the previous exercise. the blood cholesterol levels of men aged 55 to 64 are approximately Normal with mean 222 mg/dl and standard deviation 37 mg/dl. What percent of these men have high cholesterol (levels above 240 mg/dl)? What percent have borderline high cholesterol (between 200 and 240 mg/dl)? Any help on the process and how to achieve the answer would be great. Thank you
How do I answer this problem. Mean and standard deviation, finding percents?
It says The scores of the standardized test or normally distributed with a mean of 500 points and a standard deviation of 30 points. 14. What percent of test takers scored below 470? 15. What percent of test takers scored above 590? 16. What percent of test takers score between 500-560? 17. If a student was told that she ranked at the 84th percentile, what was her test score? Please help me, my teachers notes aren't helping whatsoever.
Statistics? Percent given mean and standard deviation?
Basically the higher percentage of women that are 167 centimeters tall in either country would be whichever country that 167 centimeters is a lower z-score because that would mean that there is a greater chance of a woman being greater than 167 centimeters. You have to compute the z-score of 167 centimeters in each respective country. Remember z = (given - mean)/ SD China: z = (167 - 155) / 8 = 1.5 Japan: z = (167 - 158) / 6 = 1.5 In this case they seem to have the same percentage of women that are at least 167 centimeters tall because according to the analysis we did, 167 centimeters is 1.5 standard deviations away from the mean for BOTH populations. Usually, whichever one had a lower z-score would have more women that were at least 167 centimeters tall because in a normal distribution, the farther you get away from the mean ( the more standard deviations you go out), the less people you'll see that far out.
For a standard normal distribution, find the percentage of data that are more than 2 standard deviations away from the mean?
For a standard normal distribution, find the percentage of data that are more than 2 standard deviations away from the mean.[math]\text{Z}\space\text{~}\space\text{N(}0\text{,}\space1\text{)}[/math][math]\implies1-\text{P}(-2\leq\text{Z}\leq2)[/math][math]=1-.9545=.0455=4.55\text{%}[/math]is the requested probability in percent form.This is the answer because the data can be more than [math]2[/math] standard deviations from the mean on either side of it.I used this website to obtain these probabilities:Normal DistributionNote that [math]\text{P}(-2\leq\text{Z}\leq2)[/math][math]=\text{P}(\text{Z}\leq2)-\text{P}(\text{Z}\leq-2)[/math][math]=.9772-.0228[/math][math]=.9554\text{,}[/math] with a slight difference due to rounding off, is another way to get [math]\text{P}(-2\leq\text{Z}\leq2)\text{.}[/math]Also note for a pdf like the normal, that [math]\text{P}(Z\leq\pm2)=\text{P}(\text{Z}\lt\pm2)\text{.}[/math]
Given mean and standard deviation, find top 15% of population.?
Heres the full problem: Personal best finishing times for a particular race in high school track meets are normally distributed with mean 24.6 seconds and standard deviation .64 seconds. If the qualifying time for this event for the regional championship is set so that the top 15 percent of all runners qualify, then the qualifying time in seconds is about: ____ the answer is 23.9, i just dont understand how you get that and what formula you use! thanks!!