The Smith family was one of the first to come to the U.S. They had 7 children. Assuming that the probability of a child being a girl is .5

Question

Continued: find the probability that the Smith family had:

at least 6 girls? = 0.0625

at most 6 girls? 0.9921875

I honestly don't know where to start with this question and I'm supposed to use my calculator to solve.

Answer 1

Hi Katelyn,

This is an application of the binomial probably distribution. At least 6 means 6 or 7 girls

p(k=6) + p(k=7) with 7 trials and the probability of success =.5

Look this up or calculate from the formula . p(k=6) + p(k=7)=.0625

For the next one, at most 6 means 0,1,2,3,4,5,6 . But we know that p(≤6)+p(k=7)=1 so p(k≤6)=1-p(k=7)=1-.0078125=.99218

Regards

Jim