Given two independent random samples with the following results:
n1=12 n2=18
x1=120 x2=99
s1=19 s2=23
Use this data to find the 80% confidence interval for the true difference between the population means. Assume that the population variances are equal and that the two populations are normally distributed.
Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.