# How to decide whether difference between two conditions is significant?

I'm trying to analyse an experiment I performed. I executed 9 tests measurements, at two different settings (A and B); I expect it to be normal distributed. I had the following hypotheses:

• $H_0:\; \mu_A = \mu_B$
• $H_1:\; \mu_A \neq \mu_B$

I got the following results for my measurements

• A: n=9, mean = 1.66, sd = 1.12
• B: n=9, mean = 2.48, sd = 1.16

I would like to know whether this difference is significant (say at 95%), but I get a bit stuck - I only learned how to do this when I know $\mu_A$ or $\sigma_A$ (or have a very good estimate of it due to a large sample), but I only have a sample standard deviation for A.