Question 1079155: In a Gallop Poll conducted January 30 – February 2, 2008, 43% of 18-29 year olds said that they were worried about retirement. Find the probability that out of 15 college students ages 18 – 19:
(a) Exactly 1 worried about retirement.
(b) Fewer than 5 worried about retirement.
(c) At least 10 worried about retirement.
(d) Between 8 and 10 inclusively are worried about retirement.
Answer by Boreal(15235)   (Show Source):
You can put this solution on YOUR website! 15 ways to choose 1, probability is 0.43 and the other 14 have a probability of .57 each.
multiply the three.
=0.0025
Fewer than 5:
need 0,2,4,3
0 is .43^15=3 x 10^-6, will ignore
2 is 15C2*0.43^2*0.57^13. notice how the exponents add to 15.
=0.0130
3 is 0.0426
4 is 0.0963
Sum is 0.1544. Not surprising, since the expected value is between 6 and 7
8 is 0.1470
9 is 0.0863
10 is 0.0390
inclusive is 0.2723
For at least 10
15 is <0.0001
14 is 0.0001
13 is 0.0006
12 is 0.0034
11 is 0.0134
That group is 0.0565
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