two growth hormones are being studied. a random sample of 10 rats were given the first hormone and their average weight gain was xbar1=2.3 pounds with a standard deviation of s1=0.4 pounds. For the second hormone, a random sample of 15 rats had an average weight gain of xbar2=1.9 pounds with a standard deviation of s2=0.2 pounds. Assume weight gain follows a normal distribution. Find a 90% confidence interval for the difference in mean weight gain for the two growth hormones.

I got .15lbs to .65lbs. Is this correct and if so please so process or other answer thanks