Question 856590
<pre><font face = "Tohoma" size = 3 color = "indigo"><b> 
Hi,
 p =2/3, n = 5
a) P(at least one call = 1 - P(no calls) = 1 - (1/3)^5 = .9959
b) P(no calls) = (1/3)^5 = .0041
c) P(call at least 4 days) = P(x &#8805; 4) = 1 – P(x &#8804; 3) = 1- normalcdf(5,2/3, 3)
or
Using: {{{P (x)= highlight_green(nCx)(p^x)(q)^(n-x) }}} 
P(x &#8805; 4) = P(4) + P(5) = {{{highlight_green(5)(2/3)^4(1/3)^1 + highlight_green(1)(2/3)^5(1/3)^0 }}} = .461