t test vs z test states, second, standard, references

aurific

Two samples were drawn from two normally distributed populations. For the first sample the mean was $50 and the standard deviation was $5. For the second sample, the mean was $55 and the standard deviation was $6. The first sample consists of 25 observations and the second sample consists of 36 observations.

For Ho: u1 = 48 vs Ha: u1 is not equal to 48. (u1 references the first sample)
1% level of significance

The book states a t test here is appropriate. But wouldnt the z test be appropriate since its a normal distribution even with less than 25 observations?



Edited 1 time(s). Last edit at Monday, August 17, 2009 at 01:31AM by dtrynoski.

smartpants

I think I figured it out, I assumed the sample variance was the population variance which is not the case, hence use the t test.