3.To test the claim that at most 20% of adults smoke, a recent Gallup survey of 1016 randomly selected adults showed that 21% of the respondents smoke.Identify the null and alternative hypotheses

:p0.21vs.: p >0.21

:p0.20vs.: p >0.21

:p0.20vs.: p>0.20

:p0.21vs.: p>0.20

4.Which of the following regarding the student t-distributionsaretrue?

I.Like the standard normal distribution,the t-distribution is centered at 0.

II. The spread of a t-distribution is slightly less than the corresponding normal distribution.

III.A t-distribution can be used when the population standard deviation is unknown.

II only

I and III

I only

I,II,and III