Question 914933
p(hit) .81, n = 5
a) P(x=5) = binompdf(5, .81,5) 0r .81^5
b) P(x ≤ 4) = binomcdf(5, .81, 4) Using TI
0r P = P(0) + P(1) + P(2) + P(3) + P(4)
where:
{{{P (x)= highlight_green(nCx)(p^x)(q)^(n-x) }}} 
p and q are the probabilities of success and failure respectively. 
In this case p = .81 & q = .19,  n = 5
{{{nCx = (n!)/x!(n - x)!)}}}