Exam 3: Descriptive Statistics

The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 50 hours.We can conclude that at least 75% of this brand of bulbs will last between _______.

The sample standard deviation is calculated by taking the square root of the population standard deviation.

For grouped data,the mode is the class midpoint of the modal class where the model class is the class interval with the greatest frequency.

Liz Chapa manages a portfolio of 250 common stocks. Her staff compiled the following performance statistics for two new stocks. The coefficient of variation for Salas Products,Inc.is __________.

An instructor is evaluating the performance of students on a test. He records the number of points that each student missed and created a frequency distribution. This is provided below: What is the standard deviation for this population?

According to Chebyshev's Theorem,approximately how many values in a large data set will be within 2 standard deviations of the mean?

Kurtosis is a measure of the association between two numerical variables.

A commuter travels many miles to work each morning. She has timed this trip 5 times during the last month. The time (in minutes)required to make this trip was 34,39,41,35,and 41. The median time (in minutes)required for this trip was _______.

The most frequently occurring value in a set of data is called the mode.

The empirical rule says that approximately what percentage of the values would be within 1 standard deviation of the mean in a bell shaped set of data?

An electrical component for one of the main products your company produces is specified to have an electrical impedance of 2.15 ohms.However,the manufacturing process is not perfect and there is some variation on the actual impedance of these components.A recent statistical study indicated that in fact,the impedances are normally distributed with a mean impedance of 2.15 ohms and a standard deviation of 0.05 ohms.When the impedance exceeds 2.25 ohms,the product malfunctions so that component must be rejected and replaced by one whose impedance is within the acceptable limit.If you need 1350 usable components,how many components should you order?

The number of standard deviations that a value (x)is above or below the mean is the _________________.

It is inappropriate to use the mean to analyze data that are not at least interval level in measurement.

A box and whisker plot is determined from the mean,the smallest and the largest values,and the lower and upper quartile.

Pinky Bauer,Chief Financial Officer of Harrison Haulers,Inc.,suspects irregularities in the payroll system,and orders an inspection of "each and every payroll voucher issued since January 1,1993." Each payroll voucher was inspected and the following frequency distribution was compiled. The median number of errors per voucher is __________.

The mean life of a particular brand of light bulb is 1200 hours.If you know that at about 95% of this brand of bulbs will last between 1100 and 1300 hours,then what is the standard deviation of the light bulbs' life?

According to Chebyshev's Theorem how many values in a data set will be within 3 standard deviations of the mean?

The middle value in an ordered array of numbers is called the mode.

A commuter travels many miles to work each morning. She has timed this trip 5 times during the last month. The time (in minutes)required to make this trip was 38,33,36,47,and 41. What is the variance for this sample data?

A commuter travels many miles to work each morning. She has timed this trip 5 times during the last month. The time (in minutes)required to make this trip was 34,39,41,35,and 41. The mode time required for this trip was _______.