Determine the f-percentile that is required to con- struct each of the following two-sided confidence intervals:
(a) confidence level = 95 %, degrees of freedom 12 (b) confidence level 95 %, degrees of freedom = 24 (c) confidence level 99% , degrees of freedom 13 (d) confidence level 99.9%, degrees of freedom 15

"curse these trig-loving pirates! " devora mutters as she looks at the map. then, after thinking for a moment, she walks back to the entrance of the secret cave, measuring 48 meters along the way. after performing a calculation, devora walks back to the empty treasure, faces the entrance, and turns a certain number of degrees to her left before walking 89 meters to the treasure. supposing that the angle at the cave entrance is acute and that devora's calculations were correct, how many degrees did she turn?