Question

The following information was obtained from two indepen- dent samples selected from two normally distributed populations with unknown but equal standard deviations.

n1 =21 x ̄=13.97 s1 =3.78

n2 =20 y ̄=15.55 s2 =3.26 Construct a 95% confidence interval for μ1 − μ2.

Answer 1

Given that,

For sample 1 : n1 =21 x ̄=13.97 s1 =3.78

For sample 2 : n2 =20 y ̄=15.55 s2 =3.26

Assume that, standard deviations are equal, so we used pooled standard deviation to find, the 95% confidence interval for μ1 - μ2.

Using TI-83 plus calculator we get, the 95% confidence interval for the μ1 - μ2 is, (-3.8150, 0.6548).