7.
\((1)\)某工厂生产甲、乙、丙、丁四种不同型号的产品,产量分别为\(200\),\(400\),\(300\),\(100\)件\(.\)为检验产品的质量,现用分层抽样的方法从以上所有的产品中抽取\(60\)件进行检验,则应从丙种型号的产品中抽取 件\(.\)
\((2)\)已知数列\(\{\)\(a_{n}\)\(\}\)的前\(n\)项和为\(S\)\({\,\!}_{n}\),满足\(a_{n}\)\(+3S\)\({\,\!}_{n}\)\(⋅S\)\({\,\!}_{n}\)\({\,\!}_{-1}=0(\)\(n\)\(\geqslant 2\),\(n\)\(∈N^{*})\),\(a\)\({\,\!}_{1}= \dfrac{1}{3} \),则数列\(\{\)\(a_{n}\)\(\}\)的通项公式\(a_{n}\)\(= \)______.
\((3)\)记函数\(f(x)=\sqrt{6+x-{{x}^{2}}}\)的定义域为\(D.\)在区间\(\left[ {-}4,5 \right]\)上随机取一个数\(x\),则\(x\in D\)的概率是 .
\((4)\)在\(\triangle ABC\)中,\(∠A=60^{\circ} \),\(AB=3\),\(AC=2.\)若\( \overrightarrow{BD}=2 \overrightarrow{DC} \),\( \overrightarrow{AE}=λ \overrightarrow{AC}- \overrightarrow{AB}(λ∈R) \),且\( \overrightarrow{AD}· \overrightarrow{AE}=-4 \),则\(λ \)的值为___________.