某射击选手每次射击击中目标的概率是0.8,如果他连续射击5次,则这名射手恰有4次击中目标的概率是(  )A.0.84×0.2B.C54×0.84C.C54×0.

某射击选手每次射击击中目标的概率是0.8,如果他连续射击5次,则这名射手恰有4次击中目标的概率是(  )A.0.84×0.2B.C54×0.84C.C54×0.

题型:不详难度:来源:
某射击选手每次射击击中目标的概率是0.8,如果他连续射击5次,则这名射手恰有4次击中目标的概率是(  )
答案
举一反三
A.0.84×0.2B.C54×0.84
C.C54×0.84×0.2D.C54×0.8×0.2
某人射击一次击中目标的概率为0.6,经过3次射击,设X表示击中目标的次数,则P(x≥2)等于(  )
题型:不详难度:| 查看答案
A.
B.
C.D.
(选作)某种玉米种子,如果每一粒发芽的概率为90%,播下5粒种子,则其中恰有两粒未发芽的概率约是(  )
题型:不详难度:| 查看答案
A.0.07B.0.27C.0.30D.0.33
有一批种子,每一粒发芽的概率为0.9,播下15粒种子,恰有14粒发芽的概率为(  )
题型:不详难度:| 查看答案
A.0.914B.1-0.914
C.C1514×0.914×(1-0.9)D.C1514×0.9×(1-0.9)14
抛一枚均匀硬币,正反每面出现的概率都是data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABIAAAAkCAYAAACE7WrnAAAAT0lEQVRIiWNgGAWDAygpKf2n2AAYHhwuGjWIjgYhRz9Vk8EooDJQVFR8TgwmaJCCgoIEMZgOfhp5gCr5DF0z2YZRzSBCBo8aQuVYG/plNgAlij+aimRn8QAAAABJRU5ErkJggg==,反复这样投掷,数列{an}定义如下:an=data:image/png;base64,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,若Sn=a1+a2+…+an(n∈N*)则事件“S8=2”的概率,事件“S2≠0,S8=2”的概率分别是(  )
题型:不详难度:| 查看答案
题型:不详难度:| 查看答案
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A.B.C.D.
张华同学上学途中必须经过A,B,C,D四个交通岗,其中在A,B岗遇到红灯的概率均为
1
2
,在C,D岗遇到红灯的概率均为
1
3
.假设他在4个交通岗遇到红灯的事件是相互独立的,X表示他遇到红灯的次数.
(1)若x≥3,就会迟到,求张华不迟到的概率;(2)求EX.