Question 1079327: The Internal Revenue Service is studying the category of charitable contributions. A sample of 30 returns is selected from young couples between the ages of 20 and 35 who had an adjusted gross income of more than $100,000. Of these 30 returns, 4 had charitable contributions of more than $1,000. Suppose 3 of these returns are selected for a comprehensive audit.
1.What is the probability exactly one of the three audited had a charitable deduction of more than $1,000? (Round your answer to 4 decimal places.)
2.What is the probability at least one of the audited returns had a charitable contribution of more than $1,000? (Round your answer to 4 decimal places.)
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website!
4/30*26/29*25/28*3, because the it could be 26/30*25/28*4/27 or 26/30*4/29*25/28--same results but they have to be added.
0.3202
or
denominator 30C3=4060
numerator 4C1*26C2=1300, and 1300/4060=0.3202.
---------------
At least 1: find 0 and subtract from 1. That would be 26/30/25/29*24/28=0.6404.
So at least 1 is 1-0.6404=0.3596.
|
|
|
