Probability and Statistics - Test Five
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Questions and Answers

What is the probability that the mean of a randomly selected sample equals the mean of the population?

1/16

What is the probability that your error (the distance between what you want to know and your estimate of what you want to know) is two films or less? Explain how you know this. Details are welcome.

We need to find the probability that we get a sample mean of 3, 4, 5, 6, or 7 movies. There are four samples that give us a mean of 4 films (Amy, Carlos), (Amy, Darius), (Brianna, Carlos), and (Darius, Carlos); two samples give us a mean of 7 films (Brianna, Brianna) and (Brianna, Darius); and two samples give us a mean of 3 films (Amy, Amy) and (Carlos, Carlos). Thus, 8 out of the 16 samples will give us an error less than or equal to 2. Therefore, the probability is 8/16, which is 1/2.

If we increased the sample size to nine (instead of two), what would the standard error of the sampling distribution of the mean equal? Explain your work and how you got your answer.

We can't compute a standard error since there are not nine possible samples.

In 2016, 3 sets of triplets were born in Orange County hospitals. In 2017, 0 sets of triplets were born. In 2018, 6 sets of triplets were born. In 2019, 2 sets of triplets were born. In 2020, 4 sets of triplets were born. Assuming it's a Poisson distribution, what is the probability that Orange County will have 7 sets of triplets born in 2021?

<p>0.0824</p> Signup and view all the answers

Peter wants to know the average height of male freshmen at UCI. Amy wants to know the height of all freshmen at UCI. They both randomly select students from their populations and record height until their sampling distributions become approximately normal. Who will need a larger sample before their distribution is approximately normal? Peter, Amy, or they're the same? Please explain. [Hint: Think about the shape of the population distributions.]

<p>Peter</p> Signup and view all the answers

A carnival ride can fit 36 people, and it malfunctions if the mean weight of the passengers is over 190 lbs. per passenger. The distribution of weight for park goers is normally distributed with a mean of 175 and a standard deviation of 30 lbs. If 36 park goers are randomly selected for a free ride, what's the probability that the ride will malfunction from exceeding the weight limit?

<p>0.00135</p> Signup and view all the answers

True or False and explain: A small sample (less than 10 people) taken from a population that is normally distributed will not result in a sampling distribution that is normal, while a large sample taken from the same distribution will result in a sampling distribution that is normal.

<p>False</p> Signup and view all the answers

In a town, there are four people: Amy, Bob, Carla, Dave. (This is a population.) You randomly pick one person and asks the number of homework assignments they did last week. Amy did 9, Bob did 7, Carla did 15, Dave did 9. The standard deviation of this population is 3. What is the probability that your pick will be within 2 homework assignments from the mean?

<p>0.75</p> Signup and view all the answers

I spin a spinner 10 times. The spinner has two colors: white, and black. How many possible ways (combinations) are there for landing on black 4 times?

<p>210</p> Signup and view all the answers

If the Poisson distribution is used to estimate the binomial distribution, we could just use the binomial distribution instead. When is there a distinct advantage to using the Poisson distribution, even if we can use a computer to calculate the probabilities? (Thus, efficiency and ease of use are not acceptable answers.)

<p>One distinct advantage of the Poisson distribution is in situations where the number of trials (n) of the binomial distribution is very large. The Poisson distribution may provide a more efficient way to estimate the probabilities, particularly when n is large and the probability of success (p) is small. The Poisson distribution might also be used as a good approximation for the binomial when n is large and p is small.</p> Signup and view all the answers

True or false and explain: Z-tables can only be used for normal distributions whereas z-scores can be used for any distribution.

<p>False</p> Signup and view all the answers

There is a test. It's mean is 300 with a standard deviation of 50. What is the range of the mid 60% of the distribution? Explain the steps you take to get the answer. The z-scores are between +/- 0.84 and +/- 0.85. Using either is fine.

<p>252 and 348</p> Signup and view all the answers

An archer hits the bull's-eye an average of 9/10 times. She fires 10 arrows. What is the probability that she misses the bull's-eye exactly two times? Explain the steps you take to get the answer.

<p>0.045</p> Signup and view all the answers

There is a test. The mean of the test is 75 and the standard deviation is 25. What proportion of the people got between a 94 and a 107? Explain the steps you take to get the answer.

<p>0.136</p> Signup and view all the answers

A bowl of fruit has four apples, two oranges, one banana, and three peaches. Kate reaches in and picks a piece of fruit. She then puts it back and picks another one. She does this until she has picked 150 pieces of fruit. What is the probability that she picked more than 51 apples? For the sake of the question, assume the distribution is continuous. Explain the steps you take to get the answer.

<p>0.00013</p> Signup and view all the answers

Study Notes

Probability and Statistics - Test Five

  • Population: Amy (4 movies), Brianna (10 movies), Carlos (2 movies), Darius (4 movies)
  • Sampling: Sample of 2, with replacement, order matters
  • Question 1: Probability of sample mean equaling population mean
  • Question 2: Probability of error in sample mean being 2 movies or less
  • Question 3: Standard error of sampling distribution for a sample size of 9
  • Question 4: Poisson distribution probability of 7 sets of triplets in 2021, given historical data
  • Question 5: Sample size needed for normal distribution (Peter vs. Amy) - larger sample size needed for a more diverse group
  • Question 6: Probability carnival ride malfunctions due to exceeding weight limit (normal distribution, mean weight 175 lbs, standard deviation 30 lbs, sample size 36)
  • Question 7: True or False: Small sample size (less than 10) taken from normal population does not result in a normal sampling distribution, while a large sample does.
  • Question 8: Probability of picking someone within 2 homework assignments from population mean (population size 4, standard deviation 3)
  • Question 9: Number of ways to get exactly 4 black in 10 spins (binomial)
  • Question 10: Advantages of Poisson distribution over binomial, when estimating binomial
  • Question 11: Z-tables vs z-scores (z-tables only for normal distributions)
  • Question 12: Range of mid 60% of a distribution (mean 300, standard deviation 50)
  • Question 13: Probability of missing bull's-eye exactly two times in 10 shots (binomial distribution)
  • Question 14: Proportion of people who scored between 94 and 107 in a test (mean 75, standard deviation 25)
  • Question 15: Probability of picking more than 51 apples in 150 fruit selections (Discrete distributions) / (continuous)

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Test your knowledge on various concepts in Probability and Statistics through a series of questions that cover sampling distributions, probability calculations, and the effects of sample size. This quiz includes real-world applications and theoretical scenarios to enhance your understanding. Perfect for students preparing for exams or wanting to solidify their grasp on statistical principles.

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