statistics

posted by .

If 30% of people in an area registered voters and 15 people are selected at ramdom from this area;
a. What is the probability thatexactly 3out of the15 people are registered voters?
b. What is the probability that at most 3 out of the 15 people are registered voters>
c. could we have used the normal approximation in the binomial in part b? Explain why or why not.

  • statistics -

    You can use the binomial distribution:
    P = nCs*p^s*(1-p)^n(-s) where P is the probability we are hanting for, n = 15 is the size of a sample, s is the number of registered voters of 15 people, and p = 0.3 (30%) is the proportion of registered voters in the area.
    a) P(3 of 15) = 15!/(15-3)!3!*(0.3)^3*(1 -0.3)^(15 -3) = 455*0.027*0.01384 = 0.17 or 17%;

    b) to get results for "at most 3 of the 15 people", you have to apply the above approach four times:
    P(0 of 15) =
    P(1 of 15) =
    P(2 of 15) =
    P(3 of 15) =
    then add these four probabilities together => P(at most 3 of 15);

    c) I believe that we cannot because the sample of 15 people is too small (the critical size ia about 30 items).

  • statistics -

    thank you....!!!

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. stats...please help, I don't really understand

    A college professor decides to run for Congress in a district with 450,000 registered voters. In a survey she commissioned, 58% of the 4000 registered voters interviewed indicated that they plan to vote for her. The population of interest …
  2. statistics

    A college professor decides to run for Congress in a district with 450,000 registered voters. In a survey she commissioned, 58% of the 4000 registered voters interviewed indicated that they plan to vote for her. The population of interest …
  3. math

    In a Primary election,64 out of 100 registered voters actually vote. There are 750 registered voters in one precinct. how many people in the precinct voted?
  4. math

    A candidate believes that 2/3 of the registered voters in his district will vote for him in the next election. If two registered voters are independently selected at random, find the probability that neither will vote for him in the …
  5. Statistics

    In a survey of 1233 people, 917 people said they voted in a recent presidential election. Voting records showed that 72% of eligible voters actually did vote. Given that 72% of eligible voters actually did vote, find the probability …
  6. statistics

    If 30% of people in an area are registered voters and 15 people are selected at random from the area: A. what is the probability that at most 3 out of the 15 people are registered voters?
  7. Math

    Voting In a survey of 350 registered voters in belair,123 said that they would vote for the democratic candidate for mayor. if registered voter is selected at random, what is the probability that this person will vote for the democratic …
  8. algebra

    A candidate for public office has claimed that 60% of voters will vote for her. If 5 registered voters were sampled, 1. What is the probability distribution function for this voting?
  9. statistic

    A candidate for public office has claimed that 60% of voters will vote for her. If 5 registered voters were sampled, 1. What is the probability distribution function for this voting?
  10. damon-steve- help statistics

    Statistics City XYZ has 8800 registered voters. There are two candidates: Peter and Paul. A poll of 600 randomly selected registered voters was conducted. We know that 331 said they'd vote for Peter and 251 said they'd vote for Paul. …

More Similar Questions