Source: Unpublished study by Thomas W. Lauer and Floyd G. Willoughby. (a) Construct a 95 percent confidence interval for the true difference of the means assuming equal variances. (Round your final answers to 3 decimal places. Negative values should be indicated by a minus sign.) The 95% confidence interval is from -1290.45 to -125.55 (b) Repeat part (a), using the assumption of unequal variances with Welch's formula for d.f (Round the calculation for Welch's df to the nearest integer. Round your final answers to 3 decimal places. Negative values should be indicated by a minus sign.) The 95% confidence interval is from -1313.42 O to -102.58

Source: Unpublished study by Thomas W. Lauer and Floyd G. Willoughby. (a) Construct a 95 percent confidence interval for the true difference of the means assuming equal variances. (Round your final answers to 3 decimal places. Negative values should be indicated by a minus sign.) The 95% confidence interval is from -1290.45 to -125.55 (b) Repeat part (a), using the assumption of unequal variances with Welch's formula for d.f (Round the calculation for Welch's df to the nearest integer. Round your final answers to 3 decimal places. Negative values should be indicated by a minus sign.) The 95% confidence interval is from -1313.42 O to -102.58

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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Concept explainers

Continuous Probability Distributions

Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.

Normal Distribution

Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!

Question

A special bumper was installed on selected vehicles in a large fleet. The dollar cost of body repairs was recorded for all vehicles that
were involved in accidents over a 1-year period. Those with the special bumper are the test group and the other vehicles are the
control group, shown below. Each "repair incident" is defined as an invoice (which might include more than one separate type of
damage).
Statistic
Test Group
X1 = $ 1,078
51 = $
n1 =
Control Group
X2 - $ 1,786
52 = $
n2 =
Mean Damage
Sample Std. Dev.
652
819
Repair Incidents
15
12
Source: Unpublished study by Thomas W. Lauer and Floyd G. Willoughby.
(a) Construct a 95 percent confidence interval for the true difference of the means assuming equal variances. (Round your final
answers to 3 decimal places. Negative values should be indicated by a minus sign.)
The 95% confidence interval is from -1290.45O to -125.55O
(b) Repeat part (a), using the assumption of unequal variances with Welch's formula for d.f. (Round the calculation for Welch's df to the
nearest integer. Round your final answers to 3 decimal places. Negative values should be indicated by a minus sign.)
The 95% confidence interval is from -1313.42 O to -102.58 0

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