/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 12 The candy company claims that \(... [FREE SOLUTION] | 91Ó°ÊÓ

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The candy company claims that \(16 \%\) of the Milk Chocolate M\&M's it produces are green. Suppose that the candies are thoroughly mixed and then packaged in small bags containing about \(50 \mathrm{M} \& \mathrm{M}^{\prime} \mathrm{s}\). A class of elementary school students learning about percents opens several bags, counts the various colors of the candies, and calculates the proportion that are green. a) If we plot a histogram showing the proportions of green candies in the various bags, what shape would you expect it to have? b) Can that histogram be approximated by a Normal model? Explain. c) Where should the center of the histogram be? d) What should the standard deviation of the sampling distribution be?

Short Answer

Expert verified
a) Approximately normal, b) Yes, meets normal conditions, c) Center at 0.16, d) Standard deviation is about 0.051.

Step by step solution

01

Interpret the Problem

We are looking at the distribution of the proportion of green M&M's in bags of 50 candies. Given that the company claims 16% of their M&Ms are green, we have a sample proportion problem.
02

Apply CLT for Proportions

The Central Limit Theorem (CLT) suggests that the sampling distribution of the sample proportion can be approximated by a Normal distribution if certain conditions are met: random samples, independence, large enough sample size, and np & nq ≥ 10.
03

Shape of the Histogram

a) The shape of the histogram of sample proportions should be approximately normal, given a sufficiently large sample size.
04

Check Normal Model Condition

b) We can use a Normal model if np and nq are both greater than 10. Here, n = 50, p = 0.16, so np = 50*0.16 = 8 and nq = 50*0.84 = 42, thus barely satisfying the Normal approximation conditions.
05

Determine the Center

c) The center of the histogram should be around the mean of the sample proportion, which is equal to the population proportion (p = 0.16).
06

Calculate the Standard Deviation

d) The standard deviation of the sampling distribution of the proportion is given by \( \sigma_{\hat{p}} = \sqrt{\frac{p(1-p)}{n}} = \sqrt{\frac{0.16 \cdot 0.84}{50}} \approx 0.051 \) (rounded).

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Key Concepts

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

Normal distribution
The concept of a normal distribution is fundamental in statistics. It refers to a symmetrical, bell-shaped curve used to represent the distribution of many types of data. In a perfect normal distribution, most of the data points cluster around the mean, and the probability of data points decreases as one moves away from the mean. This results in the characteristic bell shape.
For the distribution of the proportion of green M&M's from different bags, a normal distribution helps us predict outcomes. When we assume that the distribution of these proportions is approximately normal, we can make several inferences regarding their patterns and behaviors.
The normal distribution is particularly powerful because it allows us to use the properties of the curve to estimate probabilities and expectations, standard deviations, and other statistical measures. Therefore, if the conditions set by the Central Limit Theorem are met, we can confidently use a normal distribution to model our data.
Sampling distribution
The sampling distribution is a crucial concept when it comes to understanding how sample statistics can vary. It is essentially the probability distribution of a given statistic based on random sampling. In our problem, it refers to the distribution of the proportion of green M&M's when many bags are sampled.
Because we expect some variation across different samples, sampling helps us describe these variations and estimate the likely range of the population statistic. According to the Central Limit Theorem, when we have a large enough sample size and the samples are independent, the distribution of the sample proportions will be approximately normal.
In this exercise, even though the sample size of 50 is not very large, it is enough to start showing a pattern that can be approximated by a normal distribution. This helps us to predict and make conclusions about the entire population of M&M's, based on our sample data.
Proportions
Proportions are a way of expressing a part of a whole and are incredibly useful in statistics. In this exercise, the proportion refers to the number of green M&M's compared to the total number of M&M's in a bag. Since the company claims that 16% of M&M's are green, this forms our theoretical proportion value, denoted as "p".
In the context of sampling distributions, the proportion becomes a statistic called the sample proportion, denoted as "\(\hat{p}\)" (read as "p-hat"). This represents the observed ratio of green candies in each sampled bag.
Understanding proportions allows us to calculate various statistical measures, like the expected mean of the proportions and their standard deviation. This calculation involves using formulas to understand variations in our data set, helping us establish a range for normal behavior and identify outliers or unexpected patterns.
Histogram shape
A histogram is a visual representation of data distribution, using bars of different heights to show the frequency of data points within certain ranges. The shape of a histogram provides valuable insights into the nature of the data.
In our case, plotting a histogram for the proportions of green M&M's in different bags should yield an approximately normal shape. This means that most bags will have a proportion of green M&M's close to 16%, with fewer bags at the extremes having significantly higher or lower proportions.
It's crucial to consider the sample size and how the histogram shape might change with different sizes. In smaller samples, the histogram might appear slightly off from a perfect bell-shaped curve, but with larger samples, the approximation will become more accurate. This histogram is essential for understanding how well our sample data fits the expected normal distribution pattern.

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Most popular questions from this chapter

Assume that the duration of human pregnancies can be described by a Normal model with mean 266 days and standard deviation 16 days. a) What percentage of pregnancies should last between 270 and 280 days? b) At least how many days should the longest \(25 \%\) of all pregnancies last? c) Suppose a certain obstetrician is currently providing prenatal care to 60 pregnant women. Let \(\bar{y}\) represent the mean length of their pregnancies. According to the Central Limit Theorem, what's the distribution of this sample mean, \(\bar{y}\) ? Specify the model, mean, and standard deviation. d) What's the probability that the mean duration of these patients' pregnancies will be less than 260 days?

it's believed that \(4 \%\) of children have a gene that may be linked to juvenile diabetes. Researchers hoping to track 20 of these children for several years test 732 newborns for the presence of this gene. What's the probability that they find enough subjects for their study?

According to a 2013 poll from Public Policy Polling, \(4 \%\) of American voters believe that shape-shifting reptilian people control our world by taking on human form and gaining power. Yes, you read that correctly! (This was a poll about conspiracy theories.) Assume that's the actual proportion of Americans who hold that belief. a) Use a binomial model to calculate the probability that, in a random sample of 100 people, at least \(6 \%\) of those in the sample believe the thing about reptilian people controlling our world. b) Use a Normal model to calculate the same probability. How does this compare with the answer in part a? c) That same poll found that \(51 \%\) of American voters believe there was a larger conspiracy responsible for the assassination of President Kennedy. Use a binomial model to calculate the probability that, in a random sample of 100 people, at least \(57 \%\) of those in the sample believe in the JFK conspiracy theory. d) Use a normal model to calculate the same probability. How does this compare with the answer in part c? c) What do these answers tell you about the importance of checking that \(n p\) and \(n q\) are both at least \(10 ?\)

It is generally believed that nearsightedness affects about \(12 \%\) of all children. A school district has registered 170 incoming kindergarten children. a) Can you apply the Central Limit Theorem to describe the sampling distribution model for the sample proportion of children who are nearsighted? Check the conditions and discuss any assumptions you need to make. b) Sketch and clearly label the sampling model, based on the \(68-95-99.7\) Rule. c) How many of the incoming students might the school expect to be nearsighted? Explain.

The weight of potato chips in a medium size bag is stated to be 10 ounces. The amount that the packaging machine puts in these bags is believed to have a Normal model with mean 10.2 ounces and standard deviation 0.12 ounces. a) What fraction of all bags sold are underweight? b) Some of the chips are sold in "bargain packs" of 3 bags. What's the probability that none of the 3 is underweight? c) What's the probability that the mean weight of the 3 bags is below the stated amount? d) What's the probability that the mean weight of a 24 -bag case of potato chips is below 10 ounces?

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