PullingMyHairOut3

10-27-2009, 06:06 PM

Is this right? I am totally confused! My friend tried to help me and this is what we got. He told me about this forum and said maybe you could help.

Long-term history has shown that 25% of all elected offices in a rural county have been won by Democratic candidates. This year there are 4 offices up for public election in the county. Let a “success” correspond to a Democratic being elected to public office in the county and X = the number of Democrats that have been elected out of the 4 offices that were up for election.

1) What are the values of n, p, and q?

n = 4 p = 0.25 q = 0.75

2) What are the possible outcomes for the random variable X? List them in the table below.

x

--------

0

1

2

3

4

3) Using what you know about the binomial distribution and Table 3, complete the second column to create a probability distribution table.

p(x)

---------

0.316406

0.421875

0.210938

0.046875

0.003906

or do I round them for this column to equal "1"?

p(x)

----------

0.3164

0.4219

0.2109

0.0469

0.0039

4) What is the expected number of Democrats who will win office in the coming election?

n(4) x p(0.25) = 1

5) What is the standard deviation of r?

? 4x0.25x0.75 = 0.75

? 0.75 = 0.8660254037844386 = 0.866

Long-term history has shown that 25% of all elected offices in a rural county have been won by Democratic candidates. This year there are 4 offices up for public election in the county. Let a “success” correspond to a Democratic being elected to public office in the county and X = the number of Democrats that have been elected out of the 4 offices that were up for election.

1) What are the values of n, p, and q?

n = 4 p = 0.25 q = 0.75

2) What are the possible outcomes for the random variable X? List them in the table below.

x

--------

0

1

2

3

4

3) Using what you know about the binomial distribution and Table 3, complete the second column to create a probability distribution table.

p(x)

---------

0.316406

0.421875

0.210938

0.046875

0.003906

or do I round them for this column to equal "1"?

p(x)

----------

0.3164

0.4219

0.2109

0.0469

0.0039

4) What is the expected number of Democrats who will win office in the coming election?

n(4) x p(0.25) = 1

5) What is the standard deviation of r?

? 4x0.25x0.75 = 0.75

? 0.75 = 0.8660254037844386 = 0.866