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 th

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
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Chapter10: Statistics
Section10.4: Distributions Of Data
Problem 19PFA
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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? 

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