Exam 3: Describing Data Using Numerical Measures

In a recent study of the sales prices of houses in a Midwestern city, the mean sales price has been reported to be $167,811 while the median sales price was $155,600. From this information, you can determine that the data involved in the study are left-skewed.

Dynamic random-access memory (DRAM) memory chips are made from silicon wafers in manufacturing facilities through a very complex process called wafer fabs. The wafers are routed through the fab machines in an order that is referred to as a recipe. The wafers may go through the same machine several times as the chip is created. The data file DRAM Chips contains a sample of processing times, measured in fractions of hours, at a particular machine center for one chip recipe. Compute the mean processing time.

When analyzing annual incomes of adults in a market area, the marketing manager's report indicated that the 90th percentile is $123,400. That means that 90 percent of the adult incomes in the market area fall at or below $123,400.

A recent study involving a sample of 3,000 vehicles in California showed the following statistics related to the number of miles driven per day: Q1 = 12, Q2 = 45, and Q3 = 56. Based on these data, we know that the distribution is skewed.

A recent study in the restaurant business determined that the mean tips for male waiters per hour of work are $6.78 with a standard deviation of $2.11. The mean tips per hour for female waiters are $7.86 with a standard deviation of $2.20. Based on this information, which of the following statements do we know to be true?

Acme Taxi has two taxi cabs. The manager tracks the daily revenue for each cab. Over the past 20 days, Cab A has averaged $76.00 per night with a standard deviation equal to $11.00. Cab B has averaged $200.00 per night with a standard deviation of $18.00. Based on this information, Cab B has the greatest relative variation.

In the annual report, a major food chain stated that the distribution of daily sales at its Detroit stores is known to be bell-shaped, and that 95 percent of all daily sales fell between $19,200 and $36,400. Based on this information, what were the mean sales?

A large retail company gives an employment screening test to all prospective employees. If a prospective employee receives a report saying that she scored at the 40th percentile:

For a symmetric distribution, if the median value is 150 and the second quartile is 40, the fourth quartile must also be 40.

Consider the following data, which represent the number of miles that employees commute from home to work each day. There are two samples: one for males and one for females. The coefficient of variation of commute miles for the males is:

A recent study involving a sample of 3,000 vehicles in California showed the following statistics related to the number of miles driven per day: Q1 = 12, Q2 = 45, and Q3 = 56. Based on these data, if a box and whisker plot is developed, the upper limit value is 122 miles.

A major automobile maker has two models of sedans. The first model has been shown to get an average of 27 mpg on the highway with a standard deviation equal to 5 mpg. The second model gets 33 mpg on average with a standard deviation of 8 mpg. Based on this information the first car model is relatively more variable than the second car model.

Suppose a study of houses that have sold recently in your community showed the following frequency distribution for the number of bedrooms: Based on this information, the median number of bedrooms in houses sold is 3.20.

The interquartile range is the difference between the mean and the median.

The distribution of the actual weight of potato chips in a 16 ounce sack is thought to be bell-shaped with a mean equal to 16 ounces and a standard deviation equal to 0.45 ounces. Based on this, between what two limits could we expect 95 percent of all sacks to weigh?

Under what circumstances is it necessary to use the coefficient of variation to compare relative variability between two or more distributions?

The following data reflect the number of customers who test drove new cars each day for a sample of 20 days at the Redfield Ford Dealership. Given these data, what is the interquartile range?

At a sawmill in Oregon, a process improvement team measured the diameters for a sample of 1,500 logs. The following summary statistics were computed: Given this information, which of the following statements is correct?

The AMI Company has two assembly lines in its Kansas City plant. Line A produces an average of 335 units per day with a standard deviation equal to 11 units. Line B produces an average of 145 units per day with a standard deviation equal to 8 units. Based on this information, which line is relatively more consistent?

You are given the following data: Assuming that these data reflect the population of interest, these data can be considered symmetric.