Question 1170504
<pre>
This is a multinomial probability problem

{{{P(X)}}}{{{""=""}}}{{{(n!^""/((x[1])!*(x[2])!*""*""*(x[k])!))p^(x[1])p^(x[2])*""*""*""*p^(x[k])}}} where {{{x[1]+x[2]+""*""*""*""+x[k]=n}}} and {{{p[1]+p[2]+""*""*""*""+p[k]=1}}}

Here

X = the event that 2 will not purchase any beverages, 3 will purchase 1 beverage,
1 will purchase 2 beverages, and 1 will purchase 3 or more beverages.

{{{P(X)}}}{{{""=""}}}{{{expr(7!/(2!3!1!1!))0.42^2*0.33^3*0.12^1*0.13^1}}}{{{""=""}}}{{{0.0415350071}}}

Edwin</pre>