Question

求第二题的第二问如何解？

Answer 1

P(至少有6次命中）
=P(6次命中)+P(7次命中)+P(8次命中)+P(9次命中)+P(10次命中)
=(10C6)(0.75)^6.(0.25)^4+(10C7)(0.75)^7.(0.25)^3+(10C8)(0.75)^8.(0.25)^2
+(10C9)(0.75)^9.(0.25) +(10C10)(0.75)^10
=(210)(0.75)^6.(0.25)^4+(120)(0.75)^7.(0.25)^3+(45)(0.75)^8.(0.25)^2
+(9)(0.75)^9.(0.25) +(0.75)^10
=0.9031

追问

答案是0.9803

Answer 2

第二题
看不清

Answer 3

至少命中6次的情况有，命中6次，7次 ，8次，9次，10次。分别计算求和就行了。
C10(6)*0.75的6次方*0.75的4次方+C10(7)*0.75的7次方*0.75的3次方+C10(8)*0.75的8次方*0.75的2次方+C10(9)*0.75的9次方*0.75+0.75的10次方。