Statıstıcs Iı

Yanıt Açıklaması: (80-90) / sqrt( 20^2/180 + 40^2/200) =-1.82

Yanıt Açıklaması: (50 + 120) / (200 + 400) =0.28

Yanıt Açıklaması: The process of estimating a population parameter by a single number derived from the sample is called point estimation.

Yanıt Açıklaması: x = (16 + 20) / (28 + 24 + 16 + 32 + 16 + 20) = 36 / 136 = 9 / 34. pg. 25 . Correct answer is B

Yanıt Açıklaması: From the standard normal distribution given in the page 79 of your book, the answer is 1.96.

Yanıt Açıklaması: A parameter is a value that defines the characteristic of a whole population which means that population parameter consists of mean, variance, standard deviation, mode, median or proportion of the population or objects under consideration.

Yanıt Açıklaması: x = (4.1 + 5.9) / 2 = 5 . pg. 33. Correct answer is C.

Yanıt Açıklaması: The test statistic is calculated according to this formula: z = (x -µ)/(? / (n) 1/2 ). Here x=1900, µ=1000, ?=24, n=576, if we plug the numbers into the formula we would have z = (1020 -1000)/(24 / (576) 1/2 ) which is equal to 20 The answer is C

Yanıt Açıklaması: A convenience sample involves a group of individuals that is ready and available. It is also called availability sampling method. pg. 13. Correct answer is B.

Yanıt Açıklaması: Reasons Of Sampling When we try to obtain some information about the characteristics of a population there are important reasons why we use a sample instead of a census. The main reasons for sampling can be categorised by the following topics: Cost Every project has a limited funding. Time A sampling survey often provides more timely information than a census, because fewer data have to be collected and analysed. Thus, the required information can be achieved quickly. Accuracy While a census data is gathered, many unexpected problems may affect the accuracy of the results such as recording errors, copying errors, false recordings by interviewers etc. So, while working with census data, we may inadvertently come across with a figure for a population parameter being further away than the actual value. With a good sampling procedure using good sampling methods and by choosing random observations, actually we can be very close to the true value of the population parameter. Physical Impossibility Some populations are uncountable or infinite to conduct a census. In this situation, it is impossible to consider all the elements of a population. Thus, a sample is necessary to obtain information from a population. Destructive Tests If a test includes the destruction of an item or product, sampling should be used. For example, when a car manufacturer would like to get a safety rating on their cars, they send a selection of cars (3 to 5 cars) to the safety agency for testing and these cars goes under different test including a crash which demolishes the car.

Yanıt Açıklaması: To test the claims made about the population parameters or in other words to test the statistical expressions the following steps can be followed: Step 1: State null and alternate hypotheses Step 2: Select a level of significance Step 3: Identify the test statistic Step 4: Formulate a decision rule Step 5: Take a sample and make the decision

Yanıt Açıklaması: x = 160 / 640 = 0.25. pg. 25. Correct answer is D.

Yanıt Açıklaması: The null hypothesis H 0 is a statistical statement which specifies that there is a specific value of a population parameter. Generally thought as the status quo. It is what you already know about the population parameter. On the other hand, the alternative hypothesis H 1 specifies that there is a difference between the value of a population parameter and a certain value. Alternative hypothesis is also called as research hypothesis since the alternative hypothesis defines what the decision maker’s conclusion is if he/she rejects the null hypothesis. The answer is E.

Yanıt Açıklaması: A random sample of 50 power banks is selected and tested for their charging time. The sample size (n) is 50. The correct answer is D.

Yanıt Açıklaması: n1 =300, x1 = 120 then p1 = x1/n1= 120/300= 0.4 n2 =240, x1 = 150 then p2 = x2/n2= 150/240= 0.625 p = (x1 + x2)/(n1 + n2) = (120 + 150)/(240 + 300) =0.5 Then, z-test is used to test the difference between two proportions p1 and p2 and the test statistic is as follows: The numarator is 0.4 - 0.625 = -0.225. 0.5x(1-0.5)=0.25, [(1/300)+(1/600)] is assumed to be equal to 0.25 therefore the denominator is 0.25. This yields to z = -0.225/0.25 = -0.9 The answer is E.

Yanıt Açıklaması: 26 = (x + 33) / 2 ; x = 19. pg. 33. Correct answer is D.

Yanıt Açıklaması: The test statistic for a one-way ANOVA test is the ratio of two variances; namely the variance between samples (MSB) and variance within samples (MSW). Then, the test statistic F can be obtained as follows, F = MSB / MSW. Then, F = 350/70 = 5 . The correct answer is B.

Yanıt Açıklaması: I. The alternative hypothesis can be expressed in three different ways according to the purpose of the research question. (True) II. H 1 : ? ? ? 0 A hypothesis test whose alternative hypothesis (H 1 ) has this form named as the one-tailed test or one-sided alternative hypothesis. (False, H 1 : ? ? ? 0 A hypothesis test whose alternative hypothesis (H 1 ) has this form named as the two-tailed test or two-sided alternative hypothesis.) III. Right-tailed and left tailed hypothesis tests are also called a two-tailed test or two-sided alternative hypothesis. (False, Right-tailed and left tailed hypothesis tests are also called a one-tailed test or one-sided alternative hypothesis.) The answer is A.

Yanıt Açıklaması: The sampling distribution of the sample mean is the probability distribution of all possible sample means that can be created from a population with a fixed sample size of n.

Yanıt Açıklaması: In general, a hypothesis is a proposition for the specific situation encountered. Conversely a statistical hypothesis that specifies a single value for a population parameter and validity of this parameter is based on generating statistics which can be investigated by sampling distribution of the concerned information. In other words, statistical hypothesis utilizes sample statistics to determine whether a hypothesis is true or not. The correct answer is E.