Use reference angles to evaluate sec (13Pi/4) Enter the exact answers.​

Amber had 1/6 of a pie left after the bake sale. rihanna had 3/8 of a pie left. what fraction of a pie did they have altogether?

Afactory makes propeller drive shafts for ships. a quality assurance engineer at the factory needs to estimate the true mean length of the shafts. she randomly selects four drive shafts made at the factory, measures their lengths, and finds their sample mean to be 1000 mm. the lengths are known to follow a normal distribution whose standard deviation is 2 mm. calculate a 95% confidence interval for the true mean length of the shafts. input your answers for the margin of error, lower bound, and upper bound.

The ph level of a blueberry is 3.1 what is the hydrogen-ion concentration [h+] for the blueberry