Exam 3: Statistics for Describing, Exploring, and Comparing Data

Use the range rule of thumb to estimate the standard deviation. Round results to the nearest tenth. -The race speeds for the top eight cars in a 200-mile race are listed below. 188.8 183.0 189.2 182.1 175.6 184.6 178.3 179.4

Find the midrange for the given sample data. -The speeds (in mph) of the cars passing a certain checkpoint are measured by radar. The results are shown below. Find the midrange. 44.1 41.7 42.4 40.2 43.9 40.2 45.0 41.9 44.1 42.2 44.0 41.9 40.2 44.0 41.7

$\text {data set}:\quad12\quad6\quad42\quad24\quad12\quad30\quad54\quad\quad54\quad66\quad18\quad6\quad54\quad36\quad6\quad54;$ $\text { data value: } \quad42$

Find the mean for the given sample data. Unless indicated otherwise, round your answer to one more decimal place than is present in the original data values. -The local Tupperware dealers earned these commissions last month: \ 3120.40 \ 2050.85 \ 4357.05 \ 4632.26 \ 3033.20 \ 3150.18 \ 1772.68 \ 1586.15 \ 2269.53 \ 3692.16 What was the mean commission earned? Round your answer to the nearest cent.

Skewness can be measured by Pearson's index of skewness: $\mathrm { I } = \frac { 3 ( \overline { \mathrm { x } } - \text { median } ) } { \mathrm { s } }$ If $\mathrm { I } \geq 1.00$ or $\mathrm { I } \leq - 1.00$ , the data can be considered significantly skewed. Find Pearson's index of skewness for the test scores below. 68 80 36 94 72 42 75 91 84 73 88 A) $0.32$ B) $- 0.27$ C) $- 0.32$ D) $- 0.34$

Marla scored 85% on her last unit exam in her statistics class. When Marla took the SAT exam, she scored at the 85 percentile in mathematics. Explain the difference in these two scores.

A company advertises an average of 42,000 miles for one of its new tires. In the manufacturing process there is some variation around that average. Would the company want a process that provides a large or a small variance? Justify your answer.