【正确答案】 1、27    

【答案解析】利用公式D(XY)=E(XY)²一[E(XY)]²或D(XY)=D(X)D(Y)+[E(X)]² D(Y)+[E(Y)]² D(X)求之．
由题设易知
E(X)=1，D(X)=2，E(Y)=D(y)=3．
因 D(XY)=E(XY)²一[E(XY)]²=E(X² Y²)一[E(XY]² ，
又X，Y独立，故有
E(X²Y²)=E(X²)E(Y²)，E(XY)=E(X)E(Y)=1×3=3．
于是 E(X²Y²)=E(X²)E(P)=[D(X)+(E(X))²][D(Y)+(E(Y))²]
=3×12=36，
故 D(XY)=E(X²Y²)一[E(XY)]²=36一9=27．