Standard deviation - practice problems - last page
The standard deviation, symbol sigma σ, is a statistical measure of the variability of a data set. Simply put, it tells us how spread out the values are around the mean (arithmetic mean). How far away most of them are from the mean. It is a non-negative number, defined as the square root of the variance of the data. It therefore has the same dimensions as the data.Variance in statistics is the average of the squares of the deviations from the mean (mean). Variance is also a non-negative number.
The sample standard deviation is defined as the square root of the sample variance. When calculating the sample variance, for n data, only (n-1) independent data are considered.
Number of problems found: 114
- Grade point average
The average GPA is 2.78, with a standard deviation of 0.45. If GPA is normally distributed, what percentage of the students have the following GPAs? Solve for the z-score and report the appropriate percentage: a. Less than 2.30 b. Less than 2.00 c. More t
- Distribution 6399
For the statistical file: 2.3; 3.4; 1.8; 3.2; 3.2; 1.9; 3.3; 4.5; 4.3; 5.0; 4.8; 4.3; 4.3; 1.9 Determine the sample variance and the median, and from the empirical distribution function, determine P (2.1
- Distribution 6283
The life of the bulbs has a normal distribution with a mean value of 2000 hours and a standard deviation of 200 hours. What is the probability that the light bulb will last for at least 2100 hours?
- Distribution 6282
The waiting time in the buffet is governed by the normal distribution with a mean value of 130 seconds and a variance of 400. What is the probability that someone will wait less than a minute and a half?
- Variability
In the table below, the number of wrong produced goods in two shifts: morning shift: 2; 0; 6; 10; 2; 2; 4; 2; 5; 2; afternoon shift: 4; 4; 0; 2; 10; 2; 6; 2; 3; 10; Compare the variability in both shifts, compare the average number of wrong goods on both
- US GDP
Consider the following dataset, which contains the domestic US gross in millions of the top-grossing movies over the last five years. 300,452,513,550,780 I. Find the Mean of the Dataset II. Find the Squared deviation of the second observation from the mea
- Dataset
Data: 11,15,11,16,12,17,13,21,14,21,15,22 Find the dispersion of a given dataset.
- Variance and average
Of the 40 values were calculated average mx = 7.5 and variance sx = 2.25. After we found the control to lack the two items of the values of x41 = 3.8 and x42=7. Correct the above characteristics (mx and sx).
- Normal Distribution
GPAs are normally distributed at one college with a mean of 3.1 and a standard deviation of 0.4. What percentage of students at the college have a GPA between 2.7 and 3.5?
- Dispersion 3335
What is the value of the variance of the data in the file if the calculated standard deviation = 2? a) Dispersion = 6 b) Dispersion = 4 c) Dispersion = 9 d) Dispersion = 2
- Energy
In one region, the September energy consumption levels for single-family homes are normally distributed with a mean of 1050 kWh and a standard deviation of 218 kWh. Find the consumption level separating the bottom 45% from the top 55%.
- Controller
The output Controller of the company, in the control of 50 randomly selected products, found that 37 of them had no defects, eight had only one flaw, three had two defects, and two products had three defects. Determine the standard deviation and coefficie
- SD - mean
The mean is 10, and the standard deviation is 3.5. If the data set contains 40 data values, approximately how many of the data values will fall within the range of 6.5 to 13.5?
- Box and whisker plot
Construct a box and whisker plot for the given data. 56, 32, 54, 32, 23, 67, 23, 45, 12, 32, 34, 24, 36, 47, 19, 43
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