Probability

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TOTE6000

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Hi guys,
I'm confused , Can you help me,,,

Question:
After the BP oil crisis in the Gulf, sixty percent of Americans are in favor of the government’s moratorium on deepwater oil drilling. Out of the next 20 Americans interviewed,

(a) What is the probability that exactly 6 are in favor of the moratorium?
(b) What is the probability that at least 6 are in favor of the moratorium?

(c) What is the probability that no more than 6 are in favor of the moratorium?

(d) How many would you expect to be in favor of the moratorium?

(e) What is the standard deviation in the number who are in favor of the moratorium?

THANKS
 
TOTE6000 said:
Hi guys,
I'm confused , Can you help me,,,

Question:
After the BP oil crisis in the Gulf, sixty percent of Americans are in favor of the government’s moratorium on deepwater oil drilling. Out of the next 20 Americans interviewed,

(a) What is the probability that exactly 6 are in favor of the moratorium?
(b) What is the probability that at least 6 are in favor of the moratorium?

(c) What is the probability that no more than 6 are in favor of the moratorium?

(d) How many would you expect to be in favor of the moratorium?

(e) What is the standard deviation in the number who are in favor of the moratorium?

THANKS
Click to expand...

Please share your work with us, indicating exactly where you are stuck - so that we may know where to begin to help you.
 
I'm not sure:

a) Binomial with n = 20 and p = 0.6

x P( X = x )
6 0.0048544
---------------------------------------
b) Binomial with n = 20 and p = 0.6

x P( X <= x )
6 0.0064659
------------------------------------------
c) d) e) I don't know
 
Question:
After the BP oil crisis in the Gulf, sixty percent of Americans are in favor of the government’s moratorium on deepwater oil drilling. Out of the next 20 Americans interviewed,
Click to expand...


It would appear a liberal came up with this question. Statistics is great for slanting it in whatever favor the poll taker wants.

Nonetheless, this is a binomial probability problem.

(a) What is the probability that exactly 6 are in favor of the moratorium?
Click to expand...

\(\displaystyle \binom{20}{6}(.6)^{6}(.4)^{14}\)

(b) What is the probability that at least 6 are in favor of the moratorium?
Click to expand...

\(\displaystyle \sum_{k=6}^{20}\binom{20}{k}(.6)^{k}(.4)^{20-k}\)

(c) What is the probability that no more than 6 are in favor of the moratorium?
Click to expand...

\(\displaystyle \sum_{k=0}^{6}\binom{20}{k}(.6)^{k}(.4)^{20-k}\)

(d) How many would you expect to be in favor of the moratorium?
Click to expand...

This would be the mean: \(\displaystyle {\mu}=np\)

n is the number polled, p is the percentage in favor.

(e) What is the standard deviation in the number who are in favor of the moratorium?
Click to expand...

\(\displaystyle {\sigma}=\sqrt{np(1-p)}\)
 
galactus said:
Question:
After the BP oil crisis in the Gulf, sixty percent of Americans are in favor of the government’s moratorium on deepwater oil drilling. Out of the next 20 Americans interviewed,
Click to expand...

It would appear a liberal came up with this question. Statistics is great for slanting it in whatever favor the poll taker wants.
]
Click to expand...

Nope - I think one of those "cut and paste" neo-conservatives - with the drill-baby-drill mantra and "plans to save walrus in Gulf of Mexico in case of disaster"- that set up the question.

I wonder how many of those rest of the 40% will drive a car at 80 mph without seat-belt - or may be have a floating jacket for "contingency plan".
 
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