Homework Help for Statistics (page 2)

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You are studying the ages of people afflicted with acne. You collected a random sample of 49 people that have acne and recorded their ages. Using this data, you find that the sample mean age is 18.2 years and sample standard deviation is 18.3 years. Assume that the ages are normally distributed.

 

 

To find a 91% confidence interval for the ages of people with acne, what z-value would you need to use?

Answered
24 Apr 2019

 10 sour apples, 15 strawberries, 15 watermelons, 10 cherries, 13 grapes, and 25 blueberries. Inside of my gum ball machine, I have a total of 88 gum balls. After a nice dinner with my husband, we decide to end the meal with a "chew". 

1. What is the probability of the gum ball machine giving my husband a sour apple gum ball and me a strawberry one with no replacement?

2. Since my husband likes grape and I like watermelon, what is the probability of us getting the flavors we want with replacement?

For this problem we will use a standard deck of 52 cards.

What is the probability of getting 2 red face cards (Jack, Queen, or King) assuming the first one is not replaced?

What is the probability of getting 2 red face cards assuming the first one is replaced?

 

-Rochelle

Answered
22 Apr 2019

A magazine used the summated rating of 10 restaurants to predict the cost of a restaurant meal.For that data,SSR equals 131,937.29 and

R2 

Answered
21 Apr 2019

Given the plot of normal distributions A and B below, which of the following statements is true?

Select all that apply:

  • A has the larger mean.
  • B has the larger mean.
  • The means of A and B are equal.
  • A has the larger standard deviation.
  • B has the larger standard deviation.
  • The standard deviations of A and B are equal.

Answered
20 Apr 2019

In a sample of 150 men, 135 said that they had less leisure time today than they had 10 years ago. In a random sample of 250 women, 239 women said that they had less leisure time than they had 10 years ago. At α  = 0.10, is there a difference in the proportions?

Answered
17 Apr 2019

Trying to understand how to solve #2 and #4.  I know how to find the standard deviation of p-hat but I am uncertain about the 95% confidence interval.  I tried to do the formula for the standard deviation but then number 4 uses a different interval and I found that I wasn't using 95% for my answer to number 2.  What am I missing?

Answered
17 Apr 2019

While conducting experiments, a marine biologist selects water depths from a uniformly distributed collection that vary between 2.00 m and 7.00 m. What is the probability that a randomly selected depth is between 2.25 m and 5.00 m?

Answered
12 Apr 2019

A law school with a total enrollment of 5000 students is known to have 40% women in its student body.  Suppose we take a random sample of 100 students from the law school.   What value should we expect for our sample proportion of women?  What is the standard error?  According to the Central Limit Theorem should I expect the sampling distribution of the sample proportion to be approximately Normal? 

Answered
10 Apr 2019

On average, what is the correlation between the SymSpan variable and the OpSpan/ReadSpan variables? On average, what is the correlation between the OpSpan/ReadSpan variables and the CIE variable? How do I work out the missing p values?

Answered
10 Apr 2019

Researchers randomly select 30 groups from a population of woman over 70 years old. They calculate the mean height of each of these groups. The variability between these means can be attributed to

 

Answered
10 Apr 2019

The follwing gives data for the age of car and its dollar value:

a) Test using a + 0.05 to see if there is a correlation between these two variables

b)Find the equation of the regression line

c)Make a prediction for the value of the car after 6 years.

Answered
7 Apr 2019

A grading scale is set up for 1000 students test scores. It is assumed that the scores are normally distributed with a mean score of 75 and a standard deviation of 15. What is the probability a student will have a score between 45 and 75

Answered
6 Apr 2019

Write the following numbers in order from smallest to largest:  0.12, 0.3, 0.04, 0.25, 0.209

Answered
6 Apr 2019

its question 11 on the pdf that I am having trouble with 

Answered
5 Apr 2019

At 8 weeks of age kittens at a specific shelter are assessed. A vet previously noted that the average
weight of kittens (deemed healthy) at 8 weeks is 696.8 grams. A random sample of 9 kittens had an
average weight of 664.2 grams and a sample standard deviation of 71.5. She calls a colleague at an affiliated rescue in another county to see if anything is happening with their kittens at 8 weeks of age. They observe that from a sample of 22 healthy independent kittens an average weight of 735.1g with a sample standard deviation of 82.5g. Assume the distribution of kitten weights at 8 weeks is sufficiently close to the normal distribution to use the CLT, and that kittens are independent (statistically, not literally)
Question:

Suppose we anticipate equal number of kitten in shelter A and shelter B. The true di erence
in the average weights of kittens is 10.0g, and the true standard deviation were 100.0g and 120.0g,
respectively. Calculate the total sample size required in both shelters if a two-sided test is used with a5% signicance level and an 80% power is desired

Answered
5 Apr 2019