Inferential Statistics Week 2 Quiz Answer

In this article, i am gone to Share Inferential Statistics Week 2 Quiz Answer Coursera.

Week 2 Quiz

__________________________________

Question 1)
An insurance company is reviewing its current policy rates. When originally setting the rates they believed that the average claim amount was $1,800. They are concerned that the true mean is actually higher than this, because they could potentially lose a lot of money. They randomly select 40 claims, which yield a sample mean of $1,950. Which of the following is the correct set of hypotheses for this scenario?

H₀ : µ = 1,950
H_A : µ > 1,800

H₀ : x > 1,800
H_A : x > 1,800

H₀ : µ = 1,800
H_A : µ > 1,800

H₀ : µ = 1,800
H_A : µ > 1,950

Question 2)
Your friend likes to show off to his coworkers using statistical terminology, but he makes errors so much that you often have to correct him. He just completed the following hypothesis test:

H₀ : µ = 100; H_A:µ ≠ 100

X=105, s=10, n=40

P-value=0.0016

He claims the definition of this p-value is

"the probability of obtaining a sample mean of 105 from a random sample of n = 40 when the true population mean is assumed to be 100."

Which of the following is true? (You may assume his calculations are correct, only focus on his interpretation.)

Your friend is wrong, the statement should be revised as "the probability of obtaining a sample mean of 105 from a random sample of n = 40 when the true population mean is assumed to be different than 105."

Your friend is wrong, the statement should be revised as "the probability of obtaining a sample mean of 105 or more extreme from a random sample of n = 40 when the true population mean is assumed to be 100."

Your friend is wrong, the sample size is irrelevant.

Your friend is right.

Question 3)

Two-sided alternative hypotheses are phrased in terms of:

≤ or ≥

< or >

≈ or =

Question 4)

A Type 1 error occurs when the null hypothesis is

not rejected when it is true

rejected when it is true

not rejected when it is false

rejected when it is false

Question 5)

A statistician is studying blood pressure levels of Italians in the age range 75-80. The following is some information about her study:

1. The data were collected by responses to a survey conducted by email, and no measures were taken to get information from those who did not respond to the initial survey email.

2. The sample observations only make up about 4% of the population.

3. The sample size is 2,047.

4. The distribution of sample observations is skewed - the skew is easy to see, although not very extreme.

The researcher is ready to use the Central Limit Theorem (CLT) in the main part of her analysis. Which aspect of the her study is most likely to prevent her from using the CLT?

(I), because the sample may not be random and hence observations may not be independent.

(II), because she only has data from a small proportion of the whole population.

(III), because the sample size is too small compared to all Italians in the age range 75-80.

(IV), because there is some skew in the sample distribution.

Question 6)

SAT scores are distributed with a mean of 1,500 and a standard deviation of 300. You are interested in estimating the average SAT score of first year students at your college. If you would like to limit the margin of error of your 98% confidence interval to 40 points, at least how many students should you sample?

Question 7)

The significance level in hypothesis testing is the probability of

rejecting an alternative hypothesis

rejecting a true null hypothesis

failing to reject a true null hypothesis

failing to reject a false null hypothesis

rejecting a null hypothesis

Question 8)

Researchers investigating characteristics of gifted children collected data from schools in a large city on a random sample of thirty-six children who were identified as gifted children soon after they reached the age of four. The following histogram shows the distribution of the ages in months) at which these children first counted to 10 successfully. Also provided are some sample statistics.

Suppose you read online that children first count to 10 successfully when they are 32 months old, on average. You perform a hypothesis test evaluating whether the average age at which gifted children first count to 10 is different than the general average of 32 months. What is the p-value of the hypothesis test? Choose the closest answer.