Question

In a random sample of 55 newborn babies, what is the probability that 44% or fewer of the sample are boys. (use 3 decimal places). hint: you are asked to find p(p^^\^ < .44 ). to calculate this first find the z-score and then calculate the probability

Answer 1

0.053 The standard deviation of a binomial variable is sqrt(n*P*(1-P)) where n is the sample size and P is the probability of one of the outcomes. The sample size is 55 and we'll assume that both male and female are equally likely outcomes. standard deviation = sqrt(55*.5*.5) = 3.7081% 44% is 1.6181 standard deviations away from the mean of 50%. Looking this up on a standard deviation chart gives .0526 probability which we'll round to 0.053