Answered: Suppose I surveyed a random sample of…

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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Suppose I surveyed a random sample of commuters who had jobs in Manhattan, 51 whose primary mode of transportation was bus (B) or subway (S) and 80 whose primary mode was Metro-North (MN) or the Long Island Railroad (LIRR). Of the 51 in the first group, the mean annual income was $40,000 with a standard deviation of $5,100; of the 80 in the latter group, the mean annual income was $60,000 with a standard deviation of $8,000.

(a) What is the difference of the sample means (to one decimal place)?

(b) What is the standard error of the difference of sample means (to 3 decimal places)?

(c) How many degrees of freedom (df) are there?

Definition Definition Measure of central tendency that is the value that occurs most frequently in a data set. A data set may have more than one mode if multiple categories repeat an equal number of times. For example, in a data set with five item—3, 5, 5, 29, 473—the mode is 5 because it occurs twice and no other value occurs more than once. On a histogram or bar chart, the element with the highest bar represents the mode. Therefore, the mode is sometimes considered the most popular option. The mode is useful for nominal or categorical data (e.g., the most common color car that users purchase), but it is problematic for continuous data because it is more likely not to have any value that is more frequent than the other.

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