I am posting this problem here since I got to turn it in 2 hours:

It was originally posted in the probability forum for college.

the probability is 0.6 that a well driller will find a well of water at a depth less than 100 feet in a certain area. Wells are to be drilled for six new homeowners. Assue that finding a well of water at a depth of less than 100 feet is independent from drilling to drilling and that the probability is 0.6 on every drilling. If X is the number of wells of water found. Find:

1-P(X>4)

My solution: P(X>4)=1-B(4;6,0.6)

2-P(X=4)

P(X=4)=b(4;6,0.6)

3-mean

mean=n*p=3.6

4-variance

Var^2=n*p*(1-p)

5-P(X=mean)

Here since mean =3.6, I have problem to find P(X=mean)

my calculator does not give me a approximate value for b(3.6;4,0.6) !

How should I treat this question?

Thank you for your time .

B