Question

Consider the following statements. When estimating a confidence interval for the difference between the means of two independent populations.

(i) The variances in both populations of variable X are assumed to be zero.

(ii) Samples should be independently and randomly selected from the populations.

(iii) Both samples have the same variance.

	A.	Only (i) is true.
	B.	Only (ii) is true.
	C.	Both (ii) and (iii) are true.
	D.	Both (i) and (iii) are true.

Answer 1

Answer :- C. Both (ii) and (iii) are true.
Reason : The conditions mentioned in (ii) and (iii) are some of the important conditions while computing a confidence interval for the difference between the means of two independent populations using a Z or t test.
However, the condition mentioned in (i) suggests that the variance is equal to 0 i.e. there is no variability in the population which means the value of the population data set are constant, which is not the case in nature. Thus, (ii) and (iii) are true.

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