QUESTION 21 When finding a confidence interval for a population mcan hased on a

Question

QUESTION 21 When finding a confidence interval for a population mcan hased on a sample of size 8, which assumption is O A. Both populations have the same standard deviation ??. The sampling distribution of Z is normal O C. The sample population is approximately normal o.There is no special assumption made QUESTION 22 Suppose that a t-test is being conducted at the 0.05 level of significance to test IIO: mu-50 versus IHa:mu 50. A sample of size 20 is randomly selected Ihe rcjcction region is: O At> 1.725 OB.t

Explanation / Answer

Solution21:

n=8

n<30 ,small sample

use t test

conditions:

population has normal distribution or sample szie is alrge enough n>=30

samples are random and indpenedent.

Marked otion c is correct

Solution22:

H0:mu=50

H1:mu<50

left tail test

n=sample size=20

degrees of freedom =n-1=20-1=19

use t statistic as n<30

in excel type

=T.INV(0.05;19)

=-1.72913

rejection region is

t<-1.729

OPTION B

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