Rate my friend he got sum acne but it’s ight

Can someone me with #s 8, 9, and 11. with just one of the three also works. prove using only trig identities.

Suppose babies born after a gestation period of 32 to 35 weeks have a mean weight of 25002500 grams and a standard deviation of 800800 grams while babies born after a gestation period of 40 weeks have a mean weight of 27002700 grams and a standard deviation of 385385 grams. if a 3232-week gestation period baby weighs 21252125 grams and a 4040-week gestation period baby weighs 23252325 grams, find the corresponding z-scores. which baby weighs lessless relative to the gestation period?

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)