According to a study carried out by an industrial hygiene organization on 44 workers exposed to loud noise, the average sound level required to detect a 10kHz signal to detect a 10kHz signal was 32 db with a standard deviation s = 22. Determine the upper limit for an 85% confidence interval for u, the average sound level required for all individuals who are exposed to this type of Noise.

a) 38,50 b) 40,54 c) 37,46 d) 36, 77 e) 36,25