# Variance - practice problems - last page

In statistics, a variance is the expectation of the squared deviation of a random variable from its mean.Direction: Solve each problem carefully and show your solution in each item.

#### Number of problems found: 34

- Variability 29933

In September, students missed the following number of lessons: Girls: 2; 0; 7; 8; 2; 2; 4; Boys: 4; 4; 0; 3; 10; 3; 8; Compare the variability of both statistical files. - Distribution 29371

Let the random variable ξ represent the number of satisfied customers. The probability of a satisfied customer for each of the four customers is 7/10. Specify: a) probability distribution, distribution function F(x) and P(-0.5 < ξ < 3.1) b) variance - Ball bearings

One bearing is selected from the shipment of ball bearings. It is known from previous deliveries that the inner bearing radius can be considered a normal N distribution (µ = 0.400, σ2 = 25.10^−6). Calculate the probability that the selected radius will ex - Statistician 7500

A statistician monitored the variance of monthly wages and found its value to be 640,000. Determine the standard deviation of salaries if there is a one-off increase: a) about CZK 1,800, b) about 5%.

- 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? - 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 - 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).

- 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 - Controller

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 coefficient of - Distribution 2645

The worker operates 600 spindles on which the yarn is wound. The probability of tearing the yarn on each spindle at time t is 0.005. a) Determine the probability distribution of the number of torn spindles at time t and the mean and variance. b) What is t - 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? - Balls

We have n identical balls (numbered 1-n) selected without replacement. Determine 1) The probability that at least one tensile strength number coincides with the number of balls? 2) Determine the mean and variance of the number of balls, which coincides wi

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