# Variance - practice problems

In statistics, a variance is the expectation of the squared deviation of a random variable from its mean.#### Number of problems found: 23

- A sample 2

A sample of underweight babies was fed a special diet, and the following weight gains (lbs) were observed at the end of three months: 6.7, 2.7, 2.5, 3.6, 3.4, 4.1, 4.8, 5.9, and 8.3. Find the variance. (Round off to the nearest hundredths) - Summaries

A specialist teacher observes the time taken by each of the students with learning disabilities to complete a psychological task. She summaries the times using the following: Time Taken(mins) ; 1-5; 6-10; 11-12; 16-20 No. of Student ; 2 ; 4 ; 12; 4 Using - A sample

A sample of 10 randomly selected students revealed the following grades in Business Statistics first test (in a marking scale of 0 to 100): 79, 63, 60, 45, 55, 58, 59, 62, 40, 68. Examine the data using groups and presenting: a) the Histogram of the absol - Population variance

In a California community college, 60% of students will transfer to a college in the CSU system. The number of students in a sample who will transfer follows a binomial distribution. If eight students are randomly selected, find the population variance σ² - Unemployment rate

Over the last 16 years, the country's unemployment rate has changed according to the following frequency table: years of unemployment: 2 5 2 3 3 1 unemployment rate: 0.5 1 1.5 2 2.5 3 in % (percent). Determine the two-sided confidence interval for the var - Three sigma rule

The height of trees in a given stand is known to be a quantity with a normal probability distribution with a mean value of 15 m and a variance of 5 m². Determine the interval in which there will be tree heights in such a stand with a probability of 90% - Corresponding 33321

The following data on the height and the corresponding number of pupils were found in the measurement of 63 pupils: 159cm-1,161cm-1,162cm-2,163cm-1,164cm-2,165cm-2,166cm-3,167cm-2,167cm-3 6,172cm-7,173cm-9,174cm -5,175cm-2,177cm-1,178cm-4,179cm-2,181cm-1, - Marketing

Year; money spent on advertising; profit 2008 2 12 2009 5 20 2010 7 25 2011 11 26 2012 15 40 1. draw a scatter diagram depicting the data. 2. calculate the Pearson's correlation coefficient. 3. determine the linear regression equation. - IQ Intelligence quotient

Intelligence quotient (IQ) is a standardized score used as the output of standardized intelligence psychological tests to quantify a person's intelligence with the rest of the population (respectively, to a given group). Intelligence has an approximately - The shooter

The shooter shoots at the target, assuming that the individual shots are independent of each other and the probability of hitting them is 0.2. The shooter fires until he hits the target for the first time, then stop firing. (a) What is the most likely num - 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. - 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 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? - 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? - 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

Do you have homework that you can't solve? Ask a question, and we try to solve it.