设E(X)=-1,D(X)=4,由切比雪夫不等式估计概率P{-4﹤X﹤2}≥____.
5/9
:P{-4﹤X﹤2}=P{-3﹤X-E(X)﹤3}=P{∣X-E(X)∣﹤3}≥1-D(X)/9=1-4/9=5/9