please help with this question Part B asks does it to appear

Solution

sample proportion= 276 / 345 = .8...

s.d = sqrt( 0.8 * 0.2 / 345 ) = 0.021535276...

here z for 99% confidence = 2.575829...
so conf. interval= ( sample mean + or - (z* s.d) )..

99% confidence interval =  (0.7445288,0.8554712)..=( 74.45% , 85.55%)...

The usual probability of conceiving a baby who is girl is 0.5...here..we can see the confidence interval with 99% confidence is well beyong that and closer to 1 than 0.5..so the method is very effective!