# Variance - practice problems

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

- Correct mean and CV

For a group of 100 students, the mean and coefficient of variation of their marks were found to be 60 and 25, respectively. Later, it was found that the scores 45 and 70 were wrongly entered as 40 and 27. Find the corrected mean and coefficient of variati - IQ scores

IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. What percentage of the population scores higher than 125 on an IQ test? - Variance formula

Find the variance of 10,10,10,20,20,30. - Coefficient of skewness

For the data set whose Karl Pearson's Coefficient of skewness = -2.25, variance is 16, and Mean is 35, then its median value will be:

- A sample variance

Calculate the value of the sample variance. −8,−8,−3,13,4,−8,10,8 - The number 7

The number of faulty units in a carton of a particular product is known to be normally distributed with a Mean of 10 and a variance of 25. What portion of a given carton of the product is expected to contain___ faulty units? (I) less than 8 (ii) more than - Individual 82186

The average height of a member of a family of five is 1.5m, the mode of their height is 1.2m and the median is 1.6m. Find out the heights of individual members of this family if you know that they are integers in dm. - Statistical 81497

Determine the median, mode, arithmetic mean, variance, standard deviation, range of variation, and coefficient of variation of the character x in the statistical file: 2x 9, 7x 10, 9x 11, 11x 15, 15x 17, 16x 19, 13x 21, 10x 25, 9x 29, 4x 32 - Frequencies 81136

In grouped data classes such as 10-15, 16-20, 21-25, 26-30 with the respective frequencies of each class as 3, 5, 4, 3, then the range (range of variation) is: a. 15 b. 6 c. 20 d. 5

- Underweight babies

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 (on 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 - Probability 30311

There are 200 components in the production batch, of which 26 have a plus deviation from the nominal value. Calculate the probability that none of the 10 products selected will have a positive variance if we make selections without repetition

Do you have homework that you need help solving? Ask a question, and we will try to solve it.