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Find the standard deviation when the mean is 100 and 2.68 of the area lies to the right of 105?
Wiki User
∙ 11y ago
z=x-u/s
2.68=.0268 in normal distribution = .07
.07=105-100/s
s=71.4
Wiki User
∙ 11y ago
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Area to the left of the mean in a normal distribution is equal to?
One standard deviation
What percentage of the area falls below the mean?
The area between the mean and 1 standard deviation above or below the mean is about 0.3413 or 34.13%
What area within one standard deviation between and mu and minus and sigma and and mu plus and sigma?
The answer will depend on the distribution of the variable.
What percent of the scores will fall between 1.22 and 8.78 Mean 5 Standard Deviation 1.41?
Convert to Standard Normal Distribution the values of 1.22 & 8.78. Z = (8.78-5)/1.41 = 2.68; and Z = (1.22-5)/1.41 = -2.68. Find the area between 2.68 & -2.68 from Table. Area @ 2.68 = .9963; Area @ -2.68 = .0037. Take the difference in the areas and that is the solution. 0.9963 - 0.0037 = .9926 or 99.26% of the scores fall between 1.22 & 8.78.
How do you find percentiles when given standard deviation and mean?
Each standard deviation represents a certain percentile. So if we use two decimal places, −3 is the 0.13th percentile, −2 the 2.28th percentile, −1 the 15.87th percentile, 0 the 50th percentile , +1 the 84.13th percentile, +2 the 97.72th percentile, and +3 the 99.87th percentile.The mean, median and mode are all the same it the distribution is normal.BUT WHY DOES THIS WORK? HOW DO YOU DO IT?The main idea to make all this work and understandable is that the area under the normal curve is one. So if you have a SD and a mean, you can find the z score.Then, using a calculator, or a table, or even sometimes just some rules you may have learned like the empirical rule, you can find the area to the left or right of any given z score. This area is actually a percentile!So for example, if convert a data point to a z - score using the mean and standard deviation ( The formula is z=(x-mean)/standard deviation, by the way), and I look up the probability of that z-score, and say it is .25. Then it is the 25th percentile.The table below gives you all the percentiles and their corresponding z scores.z-score percentile for normal distributionPercentilez-ScorePercentilez-ScorePercentilez-Score1-2.32634-0.412670.442-2.05435-0.385680.4683-1.88136-0.358690.4964-1.75137-0.332700.5245-1.64538-0.305710.5536-1.55539-0.279720.5837-1.47640-0.253730.6138-1.40541-0.228740.6439-1.34142-0.202750.67410-1.28243-0.176760.70611-1.22744-0.151770.73912-1.17545-0.126780.77213-1.12646-0.1790.80614-1.0847-0.075800.84215-1.03648-0.05810.87816-0.99449-0.025820.91517-0.954500830.95418-0.915510.025840.99419-0.878520.05851.03620-0.842530.075861.0821-0.806540.1871.12622-0.772550.126881.17523-0.739560.151891.22724-0.706570.176901.28225-0.674580.202911.34126-0.643590.228921.40527-0.613600.253931.47628-0.583610.279941.55529-0.553620.305951.64530-0.524630.332961.75131-0.496640.358971.88132-0.468650.385982.05433-0.44660.412992.326
How do you calculation standard deviation of concrete cubes?
You cannot calculate standard deviation for objects such as concrete cubes - you can only calculate standard deviation for some measure - such as side length, surface area, volume, mass, alkalinity or some other measure.
Area to the left of the mean in a normal distribution is equal to?
One standard deviation
Find the area under a normal distribution curve that lies within one standard deviation of the mean is approximattely?
The area under N(0,1) from -1 to 1 = 0.6826
What percentage of the area falls below the mean?
The area between the mean and 1 standard deviation above or below the mean is about 0.3413 or 34.13%
What is the standard deviation for fico scores?
The answer will depend on what the variable is: turnover, profit, floor area, number of customers, etc.
What is the area within the normal curve between -1SD and plus 1 SD?
The area within the normal curve between -1 standard deviation (SD) and +1 SD is approximately 68%. This means that about 68% of the data falls within one standard deviation of the mean in a normal distribution.
What area within one standard deviation between and mu and minus and sigma and and mu plus and sigma?
The answer will depend on the distribution of the variable.
What is the empirical rule for 1 and 2 standard deviations?
The empirical rule is 68 - 95 - 99.7. 68% is the area for +/- 1 standard deviation (SD) from the mean, 95% is the area for +/- 2 SD from the mean; and 99.7% is the area for +/- 3 SD from the mean.
Find the area under the standard normal curve to the right of z equals 1?
From the table in the related link, the value at z equal one is 0.3413. The area then to the right of z equal one is 0.5 - 0.3413, or 0.1587.
How do you find the perimeter of a right angled triangle using the area?
how to find the perimeter of a right angled triangle using the area
What percent of the scores will fall between 1.22 and 8.78 Mean 5 Standard Deviation 1.41?
Convert to Standard Normal Distribution the values of 1.22 & 8.78. Z = (8.78-5)/1.41 = 2.68; and Z = (1.22-5)/1.41 = -2.68. Find the area between 2.68 & -2.68 from Table. Area @ 2.68 = .9963; Area @ -2.68 = .0037. Take the difference in the areas and that is the solution. 0.9963 - 0.0037 = .9926 or 99.26% of the scores fall between 1.22 & 8.78.
What is the qualifying time for the fastest 5 percent of all runners if the average finishing time is 5 minutes 17 seconds with standard deviation of 12 seconds?
Assuming a normal distribution: For the fastest 5% we need to find the z value which gives 100% - 5% = 95% of the area under the normal curve (from -∞). Using single tailed tables, we need the z value which gives 95% - 50% = 0.45 (above the mean); this is found to be z ≈ 1.645 z = (value - mean)/standard deviation → value = mean + z × standard deviation ≈ 5 min 17 sec + 1.645 × 12 sec ≈ 5 min 17 sec + 20 s = 5 min 37 sec
