Studies have shown that heating the scrotum by just 1◦C can reduce sperm count and sperm quality, so men concerned about fertility are cautioned to avoid too much time in the hot tub or sauna. A new study suggests that men also keep their laptop computers off their laps. The study measured scrotal temperature in 29 healthy male volunteers as they sat with legs together and a laptop computer on the lap. Temperature increase in the left scrotum over a 60-minute session is given as 2.31 ± 0.96 and a note tells us that ‘‘Temperatures are given as ◦C; values are shown as mean ± SD.” The abbreviation SD stands for standard deviation. (Men who sit with their legs together without a laptop computer do not show an increase in temperature.)

(a) If we assume that the distribution of the temperature increases for the 29 men is symmetric and bell-shaped, find an interval that we expect to contain about95%of the temperature increases.

(b) Find and interpret the z-score for one of the men, who had a temperature increase of 4.9◦.