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Sixty-five percent of all male voters and \(40 \%\) of all female voters favor a particular candidate. A sample of 100 male voters and another sample of 100 female voters will be polled. What is the probability that at least 10 more male voters than female voters will favor this candidate?

Short Answer

Expert verified
The exact probability would require computing the summation in the formula from step 4, which will depend on the exact binomial probability values from step 3. As this involves some computation, an exact numerical value isn't provided here. However, once you perform these calculations, you will have your answer.

Step by step solution

01

Binomial Distribution Parameters

Firstly, determine the parameters for the binomial distribution. For male voters it is \(n1=100\), \(p1=0.65\) and for female voters it is \(n2=100\), \(p2=0.40\). 'n' is the number of trials and 'p' is the probability of success on each trial.
02

Use Binomial Probability Formula

Use the binomial probability formula: \[P(X=k) = \binom{n}{k}p^k(1−p)^{n−k}\] where \(X\) is the random variable, \(n\) is the number of trials, \(k\) is the number of successful trials and \(p\) is the probability of success on each trial.
03

Calculate Individual Probabilities

Calculate the probabilities for male and female voters individually. For example, to calculate the probability of exactly k men favoring the candidate: \[P(M=k) = \binom{n1}{k}p1^k(1−p1)^{n1−k}\] Similarly calculate for female voters.
04

Probability of At least 10 more male voters

We need to calculate the cumulative probability that at least 10 more men favor the candidate than women. This involves summing over all valid 'k': \[P(M≥W+10) = \sum_{k=0}^{100}\sum_{j=0}^{k-10} P(M=k)P(W=j)\]
05

Calculate the Probability

Use the formula from step 4 to calculate the probability. This involves using the binomial probabilities from step 3 and summing over valid numbers of male and female voters who favor the candidate.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Probability
Probability is a fundamental concept in statistics, describing the chance or likelihood of an event happening. Imagine flipping a coin. There are two possible outcomes: heads or tails. The probability of each is 0.5, as the coin has no memory of past flips.

Probability is calculated using the formula:
  • For a single event: \[P(E) = \frac{\text{Number of favorable outcomes}}{\text{Total number of possible outcomes}}\]
  • For multiple events: consider the binomial distribution, which we'll discuss in a moment.
Understanding probability helps in making predictions and informed decisions. In voter statistics, it estimates how many people might vote for a particular candidate. In our problem, we used probabilities to estimate how many voters from different groups support the candidate.
Voter Statistics
Voter statistics involve analyzing data related to voting behavior, such as the likelihood of individuals supporting a specific candidate. These statistics help in understanding public opinion and making electoral predictions.

In our exercise, we have:
  • 65% of all male voters favoring the candidate
  • 40% of all female voters favoring the candidate
These percentages are crucial because they define the probability 'p' in the binomial distribution for each group. Collecting accurate voter statistics is essential for politicians and analysts when forecasting election outcomes. By sampling the population, like the groups of 100 male and 100 female voters, we get a sense of the whole population's voting behavior. This sampling method provides insights, allowing statistical analysis to make predictions based on smaller subsets.
Cumulative Probability
Cumulative probability refers to the probability that a random variable takes a value less than or equal to a specific value. It's essential when we want to calculate probabilities over a range of outcomes, rather than for individual events.

In our exercise, cumulative probability helps find the chance that at least 10 more male voters than female voters support the candidate. We used:
\[P(M \geq W+10)\] This sums up the probabilities for all scenarios where 10 or more male voters favor the candidate compared to female voters. Cumulative probability is particularly useful when dealing with complex scenarios, as it allows us to aggregate multiple probabilities into a single measure. In practice, this involves adding individual probabilities over a range of outcomes.
Statistical Analysis
Statistical analysis is the process of collecting, examining, and interpreting data to uncover patterns and trends. It's a powerful tool for making informed decisions in various fields, from economics to healthcare.

In our problem involving voter statistics, we used statistical analysis to assess probabilities through the lens of the binomial distribution. By defining each group of voters' parameters and probabilities, we established a framework to calculate complex probabilities. The analysis involved:
  • Determining the probability parameters for male and female voters.
  • Calculating binomial probabilities to find the chances of specific voting outcomes.
  • Using these probabilities to determine cumulative outcomes.
Statistical analysis in this context enables us to predict behaviors by considering the uncertainties inherent in any voting process, offering insights into the likely support a candidate might receive among different demographic groups.

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Most popular questions from this chapter

According to the information given in Exercise \(10.25\), a sample of 45 customers who drive luxury cars showed that their average distance driven between oil changes was 3187 miles with a sample standard deviation of \(42.40\) miles. Another sample of 40 customers who drive compact lower-price cars resulted in an average distance of 3214 miles with a standard deviation of \(50.70\) miles. Suppose that the standard deviations for the two populations are not equal. a. Construct a \(95 \%\) confidence interval for the difference in the mean distance between oil changes for all luxury cars and all compact lower-price cars. b. Using a \(1 \%\) significance level, can you conclude that the mean distance between oil changes is lower for all luxury cars than for all compact lower- price cars? c. Suppose that the sample standard deviations were \(28.9\) and \(61.4\) miles, respectively. Redo parts a and b. Discuss any changes in the results.

The owner of a mosquito-infested fishing camp in Alaska wants to test the effectiveness of two rival brands of mosquito repellents, \(\mathrm{X}\) and \(\mathrm{Y}\). During the first month of the season, eight people are chosen at random from those guests who agree to take part in the experiment. For each of these guests, Brand \(\bar{X}\) is randomly applied to one arm and Brand \(\mathrm{Y}\) is applied to the other arm. These guests fish for 4 hours, then the owner counts the number of bites on each arm. The table below shows the number of bites on the arm with Brand \(X\) and those on the arm with Brand \(Y\) for each guest. \begin{tabular}{l|rrrrrrrr} \hline Guest & A & B & C & D & E & F & G & H \\ \hline Brand X & 12 & 23 & 18 & 36 & 8 & 27 & 22 & 32 \\ \hline Brand Y & 9 & 20 & 21 & 27 & 6 & 18 & 15 & 25 \\ \hline \end{tabular} a. Construct a \(95 \%\) confidence interval for the mean \(\mu_{d}\) of population paired differences, where a paired difference is defined as the number of bites on the arm with Brand \(X\) minus the number of bites on the arm with Brand \(Y\). b. Test at a \(5 \%\) significance level whether the mean number of bites on the arm with Brand \(\mathrm{X}\) and the mean number of bites on the arm with Brand \(Y\) are different for all such guests.

Refer to Exercise \(10.95 .\) Suppose Gamma Corporation decides to test govemors on seven cars. However, the management is afraid that the speed limit imposed by the governors will reduce the number of contacts the salespersons can make each day. Thus, both the fuel consumption and the number of contacts made are recorded for each car/salesperson for each week of the testing period, both before and after the installation of governors. \begin{tabular}{c|cc|cc} \hline \multirow{2}{*} { Salesperson } & \multicolumn{2}{|c|} { Number of Contacts } & \multicolumn{2}{|c} { Fuel Consumption (mpg) } \\ \cline { 2 - 5 } & Before & After & Before & After \\ \hline A & 50 & 49 & 25 & 26 \\ B & 63 & 60 & 21 & 24 \\ C & 42 & 47 & 27 & 26 \\ D & 55 & 51 & 23 & 25 \\ E & 44 & 50 & 19 & 24 \\ F & 65 & 60 & 18 & 22 \\ G & 66 & 58 & 20 & 23 \\ \hline \end{tabular} Suppose that as a statistical analyst with the company, you are directed to prepare a brief report that includes statistical analysis and interpretation of the data. Management will use your report to help decide whether or not to install governors on all salespersons' cars. Use \(90 \%\) confidence intervals and 05 significance levels for any hypothesis tests to make suggestions. Assume that the differences in fuel consumption and the differences in the number of contacts are both normally distributed.

A random sample of nine students was selected to test for the effectiveness of a special course designed to improve memory. The following table gives the scores in a memory test given to these students before and after this course. \begin{tabular}{l|lllllllll} \hline Before & 43 & 57 & 48 & 65 & 81 & 49 & 38 & 69 & 58 \\ \hline After & 49 & 56 & 55 & 77 & 89 & 57 & 36 & 64 & 69 \\ \hline \end{tabular} a. Construct a \(95 \%\) confidence interval for the mean \(\mu_{d}\) of the population paired differences, where a paired difference is defined as the difference between the memory test scores of a student before and after attending this course. b. Test at a \(1 \%\) significance level whether this course makes any statistically significant improvement in the memory of all students.

A November 2011 Pew Research Center poll asked American social media users about their use of social media (such as Facebook, Twitter, MySpace, or LinkedIn). The study is based on a national telephone survey of 2277 adult social media users conducted from April 26 to May 22, 2011 (www.pewinternet. org/Reports/201 1/Why-Americans-Use-Social-Media/Main-reportaspx). According to this survey, \(16 \%\) of 30 - to 49 -year-old and \(18 \%\) of \(50-\) to 64 -year-old social media users cited connecting with others with common hobbies or interests as a major reason for using social networking sites. Suppose that this survey included 562 social media users in the 30 to 49 age group and 624 in the 50 to 64 age group. a. Let \(p_{1}\) and \(p_{2}\) be the proportions of all social media users in the age groups 30 to 49 years and 50 to 64 years, respectively, who will cite connecting with others with common hobbies or interests as a major reason for using social networking sites. Construct a \(95 \%\) confidence interval for \(p_{1}-p_{2}\). b. Using a \(1 \%\) significance level, can you conclude that \(p_{1}\) is different from \(p_{2}\) ? Use both the criticalvalue and the \(p\) -value approaches.

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