Ünite Sınavı Soruları

(Answer the question 7, 8 and 9 according to those information)

Consider the following hypothesis:

H0: μ = 80

H1: μ ≠ 80

A random sample of 16 observations is randomly selected from normally distributed population. The mean of the sample is 90 and the standard deviation of the sample is 5. Test the null hypothesis given above with %95 confidence level.

What is the critical value for that test procedure?

what is the last step of hypothesis testing?

In an investigation, if the significance level is 0,01 ; what is the confidence level of this study ? 

1. Identify the test statistic
2. Select a level of significance
3. State null and alternate hypotheses
4. Take a sample and make the decision
5. Formulate a decision rule

Which one of the following alternatives indicate the correct order of hypothesis testing steps?

A power bank’s charging time is 5 hours. 50 power banks are selected and tested for their charging time. The average charging time of these power banks is 5.05 hours. It’s assumed that the power bank charging time is normally distributed with a standard deviation as σ = 0.2 hours. 

What is the sample size (n) according to the situation above?

If a researcher fails to reject the null hypothesis (H₀) and the H₀ is false what can be said?

I. There are four possible correct and incorrect decision-making situations that may occur through statistical hypothesis testing.

II. Type I error is defined as failing to reject the null hypothesis (H₀) when it is actually false.

III.  Type II error is defined as rejecting the null hypothesis (H₀) when it is actually true.

Which of the given statements about incorrect decisions through hypothesis testing can be said to be true?

The price of a certain electronic product at a chain store is 180 TL. The same electronic product is also available through various online stores and five of the store prices are as follows: 155, 179, 175, 175, 161 TL. Let’s assume that online prices are normally distributed and  at the significance level α = 0.1. 

Given the information above, what can we conclude about the mean online store price of the product?

In an investigation, if the confidence level is 0,95 ; what is the significance level of this study?

I. The mean, median and mode of the t distribution are all equal to zero.

II. The t distribution is bell-shaped and symmetrical. The total area under a t-curve is 1 or  100%

III. As the degrees of freedom decreases, the shape of the t-distribution approaches to the standard normal distribution.

Which of the given statements about properties of the t-distribution are true?

I. The alternative hypothesis can be expressed in three different ways according to the purpose of the research question.

II. H₁: θ ≠ θ₀  A hypothesis test whose alternative hypothesis (H₁) has this form named as the one-tailed test or one-sided alternative hypothesis.

III. Right-tailed and left tailed hypothesis tests are also called a two-tailed test or two-sided alternative hypothesis.

Which of these statements about hypothesis testing are true?

I.  The null hypothesis defines what the decision maker’s conclusion is if he/she accepts the alternative hypothesis. 

II. The null hypothesis H₀ is a statistical statement which specifies that there is a specific value of a population parameter.

III. The alternative hypothesis H₁ specifies that there is a difference between the value of a population parameter and a certain value. 

Which of the given statements can be said about the null and alternative hypotheses?

In which situation below, can hypothesis tests for proportions be used?

(Answer the questions 9 and 10 according to following information)

A sales manager assesses that %60 of their costumers are happy with their product. A sample of 150 customers were selected randomly and it was found that 80 of them are happy with the product. Test the sales manager assessment at %95 confidence level.

What is the test statistic at this hypothesis testing?

Which of the following is NOT a statistical hypothesis?

what do we call "P(fail to reject the null hypothesis H₀ when it is actually false)"?

There are two types of incorrect decisions through hypothesis testing. Which of the following describes "type I error"?

What is a statistical statement which specifies that there is a specific value of a population parameter?

The price of a certain electronic product at a chain store is 180 TL. The same electronic product is also available through various online stores and five of the store prices are as follows: 155, 179, 175, 175, 161 TL. 

What is the null hypothesis for the problem given above?