n a study of exhaust emissions from school buses, the pollution intake by passengers was determined for a sample of nine school buses used in the Southern California Air Basin. The pollution intake is the amount of exhaust emissions, in grams per person, that would be inhaled while traveling on the bus during its usual 18-mile trip on congested freeways from South Central LA to a magnet school in West LA. Here are the amounts for the nine buses when driven with the windows open. 1.17 0.33 0.40 0.33 1.32 0.38 0.25 0.40 0.35 (a) Consider making a stemplot. Are there outliers or strong skewness that would preclude use of the t procedures? Which is correct? A. The sample is small and the stemplot is right skewed with possible outliers, so use of t procedures is not appropriate. b. The distribution is symmetric so use of t procedures is appropriate. c. The sample is small and the stemplot is left skewed with possible outliers, so use of t procedures is not appropriate. d.The distribution has a slight right skew, but no potential outliers, so the use of t procedures is still appropriate. (b) A good way to judge the effect of outliers is to do your analysis twice, once with the outliers and a second time without them. Give a 90% confidence interval, with all the data, for the mean pollution intake among all school buses used in the Southern California Air Basin that travel the route investigated in the study. Low= high= Give a 90% confidence interval with the outliers removed. Low= high= (c) Compare the two intervals in part (b). Which is correct ? a. What is the most important effect of removing the outliers? B.Without the outliers, there is a smaller margin of error.Without the outliers, there is a larger margin of error.

MATLAB: An Introduction with Applications

6th Edition

ISBN:9781119256830

Author:Amos Gilat

Publisher:Amos Gilat

Chapter1: Starting With Matlab

Section: Chapter Questions

Problem 1P

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In a study of exhaust emissions from school buses, the pollution intake by passengers was determined for a sample of nine school buses used in the Southern California Air Basin. The pollution intake is the amount of exhaust emissions, in grams per person, that would be inhaled while traveling on the bus during its usual 18-mile trip on congested freeways from South Central LA to a magnet school in West LA. Here are the amounts for the nine buses when driven with the windows open.

1.17 0.33 0.40 0.33 1.32 0.38 0.25 0.40 0.35

(a) Consider making a stemplot. Are there outliers or strong skewness that would preclude use of the t procedures? Which is correct?

A. The sample is small and the stemplot is right skewed with possible outliers, so use of t procedures is not appropriate.

b. The distribution is symmetric so use of t procedures is appropriate.
c. The sample is small and the stemplot is left skewed with possible outliers, so use of t procedures is not appropriate.

d.The distribution has a slight right skew, but no potential outliers, so the use of t procedures is still appropriate.

(b) A good way to judge the effect of outliers is to do your analysis twice, once with the outliers and a second time without them. Give a 90% confidence interval, with all the data, for the mean pollution intake among all school buses used in the Southern California Air Basin that travel the route investigated in the study.

Low=
high=

Give a 90% confidence interval with the outliers removed.
Low=
high=

(c) Compare the two intervals in part (b). Which is correct ?

a. What is the most important effect of removing the outliers?

B.Without the outliers, there is a smaller margin of error.Without the outliers, there is a larger margin of error.

Definition Definition Measure of central tendency that is the average of a given data set. The mean value is evaluated as the quotient of the sum of all observations by the sample size. The mean, in contrast to a median, is affected by extreme values. Very large or very small values can distract the mean from the center of the data. Arithmetic mean: The most common type of mean is the arithmetic mean. It is evaluated using the formula: μ = 1 N ∑ i = 1 N x i Other types of means are the geometric mean, logarithmic mean, and harmonic mean. Geometric mean: The nth root of the product of n observations from a data set is defined as the geometric mean of the set: G = x 1 x 2 ... x n n Logarithmic mean: The difference of the natural logarithms of the two numbers, divided by the difference between the numbers is the logarithmic mean of the two numbers. The logarithmic mean is used particularly in heat transfer and mass transfer. ln x 2 − ln x 1 x 2 − x 1 Harmonic mean: The inverse of the arithmetic mean of the inverses of all the numbers in a data set is the harmonic mean of the data. 1 1 x 1 + 1 x 2 + ...

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