Question

In a test of a​ gender-selection technique, results consisted of 215 baby girls and 20 baby boys. Based on this​ result, what is the probability of a girl born to a couple using this​ technique? Does it appear that the technique is effective in increasing the likelihood that a baby will be a​ girl?

Does the technique appear effective in improving the likelihood of having a girl​ baby?

Answer 1

1)from above probability of a girl born to a couple using this​ technique phat =215/235=0.9149

2) here let technique is ineffective and probability of having a girl child p=0.5

therefore standard deviation of proportion =sqrt(p*(1-p)/n)=sqrt(0.5*0.5/235)=0.0326

here as proportion 0.907 falls more then 2 standard deviation from assumed mean of 0.5 ; therefore it is an highly usual event or having a very small probability of happening by chance

hence the technique is effective in increasing the likelihood that a baby will be a​ girl.