statistics t test
posted by Anonymous .
how to know exact t value using sample standard deviation and sample mean and sample size
i think df is sample size 1 .
we usually use approx value but to use exact value how to use t score table.
and how we conclude whether it is two tailed test or one tailed test .
(i f the problem asks for exact increase or decrease ,is it one tailed test ,i guess so ,)
please clarify my doubts

Yes, df = n1
For twotailed test:
Ho: mean = X
Ha: mean ≠ X
For onetailed test:
Ho: mean < or = X
Ha: mean > X
or
Ho: mean > or = X
Ha: mean < X
Ho = null hypothesis
Ha = alternative hypothesis 
how do we know it is one tailed test or two tailed test?

What are your hypotheses? That determines difference between onetailed and twotailed (see my previous post).

the average weekly earnings of a production worker were $424. to know if wages, on average, have gone up since that time. To test this, you sample 64 production workers, and determine that their average salary is $432.69, with a sample standard deviation of $33.90. Use a 0.05 level of significance .carry out test .
is it t test or z test ? how would we know
in this case one tailed or two tailed how can we know? 
If a population proportion is 0.29 and if the sample size is 120, 25% of the time the sample proportion will be less than what value if you are taking random samples?
Round your answer to 2 decimal places, the tolerance is +/0.01.