Question

I need to solve this question using excel.

Suppose that individuals with a certain gene have 70% probability of eventually contracting a certain disease. If 100 individuals with the gene participate in lifetime study, what is the probability that 70 or more of them eventually contract the disease?

Answer 1

here this can be used two ways: excel formula are in bold:

1)

Binomial distribution:

probability that 70 or more of them eventually contract the disease

=1-binomdist(69,100,0.7,true)=0.5491

2)

Nomal approximation with continuity correction:

here mean of distribution=μ=np=	70.00
and standard deviation σ=sqrt(np(1-p))=	4.5826

  probability that 70 or more of them eventually contract the disease

=1-norm.dist(69.5,70,4.5826,true)=0.5434