# Help!

#### mkelly

##### New Member
I have been working on this for almost 24 hours! Can someone please help me with this problem...
here's what i have gotten so far:

this is for two different processes for producing precision ball bearings that a company is experimenting with:
Process A ProcessB
Mean: .002mm .0026mm
SD: .0001mm .00012mm
Sample Size: 12 14

now for the question:
what is the critical t value at the 1% level of significance and what is the computed value of t?

can anyone help me with this! i have been around and around with this!!!!
thanks!

#### F.A.P

##### New Member
mkelly said:
what is the critical t value at the 1% level of significance and what is the computed value of t?
thanks!
First you must state what hypothesis you are testing and what alternative hypothesis you have. *

For example, H0: mean1 - mean2 = 0, against H1: mean1 - mean2 < 0

Then when you compute the test statistic t, you should take into account that you have two populations of different sizes. That is, you should use a pooled estimator for sigma^2.

The two samples contributes with n1-1 and n2-1 degrees of freedom to your estimator. This, together with alpha and *, will determine the critical t-value for your test.