Question 957900
First you need to solve for the number of coins. 
The combination that works is 
2 Q, 1 D, 1 N and 1 P.
So then,
{{{P(N)=1/6}}}
{{{P(Q)=2/6=1/3}}}
So then,
{{{P=P(N)*P(Q)}}}
{{{P=(1/6)(1/3)}}}
{{{P=1/18}}}