I need help figuring out the calculations for this problem P

I need help figuring out the calculations for this problem. Please be as detailed as possible.

Question #48 The following data give the recovery of bomide from spiked samples of vegetable matter, measured by using a chro matographic method. The same amount of bromide was added to each specimen. A t-test needs to be per formed to compare the mean recoveries of bromide from these two types of vegetables. For this, this critical value of t should be used at 95% confidence level: (1) 2.228; (2) 2.131; (3) 2.262; (4) None of the above

Solution

You need to look at a t table of critical values for this. We are interested in a 95% confidence interval, so there will be .025 probability on each tail. Since there are 6 observations in each group, we subtract 1 then multiply by 2 for 2 groups to calculate degrees of freedom. (6-1)*2=10 DF. Finding .025 and DF=10 on the table will yield a critical value of 2.228.