8. Incorrect. The answer is false not true.
The confidence interval is
b +/- t*(n-2)-0.5*(sy.x/sx), where t = +/- t0.975,6= +/- 2.45.
0.636 +/-2.45*6-0.5*(0.5641/4.062) = 0.636 +/-0.1389 is the 95% confidence level for b.