Let A & B be two events. Suppose `P(A) = 0.4` , `P(B) = p` and `P(AuuB)=0.7` The value of `p` for which `A` and `B` are independent is
A. `1//3`
B. `1//4`
C. `1//2`
D. `1//5`
Clearly P(A) = `1//3`, `P(A uu B) = 3//4`. Now, `P(B) le P(A uu B)` `implies P(B) le 3//4 " "(1)` Also, P(B) = `P(A uu B) - P(A) +...
2 Answers 1 viewsCorrect Answer - A We are given that `P(AnnB)=P(A)P(B)` `P(BnnC)=P(B)P(C)` `P(CnnA)=P(C)P(A)` `P(AnnBnnC)=P(A)(B)P(C)` We have, `P(Avv(BnnC)=P(A)(B)P(C)=P(A)P(B)P(C)=P(A)P(BnnC)` `impliesA and BnnC` are independent Therefore, `S_(2)` is true. Also, `P[(Ann(BuuC)]=P[(AnnB)uu(AnnB)nn(AnnC)]` `=P(AnnB)+P(AnnC)-P(AnnBnnC)` `=P(A)P(B)+P(A)P(C)-P(A)P(B)P(C)` `P(A)[P(B)+P(C)-P(B)P(C)]` `P(A)[P(B)+P(C)-P(BnnC)]` `=P(A)P(BnnC)`
2 Answers 1 viewsCorrect Answer - A `P(AnnC)=P(A)P(C)` `or1/20=1/5P(C)` `orP(C)=1/4` Now, `P(BuuC)=1/6+1/4-P(BnnC)` `P(BnnC)=5/12-3/8=1/24P(BnnC)` Therefore, B and C aer independent.
2 Answers 1 viewsCorrect Answer - B `P(S//T)=(P(SnnT))/(P(T))` `or 0.5=(P(SnnT))/(0.69)` ` or 0.5=(P(SnnT))/(0.69)` `or P(SnnT)=0.5xx0.69=P(S)P(T)` Therefore, S and T are independent. `thereforeP(Aand T)=P(S)P(T)` ` =0.69xx0.5=0.345` `P(SorT)=P(S)+P(T) -P(SnnT)` `=0.5+0.69-0.345 =08450`
2 Answers 1 viewsCorrect Answer - 2 When A and B are mutually exclusive, `P(AnnB)=0` `thereforeP(AuuB)=P(A)+P(B)" "(1)` `implies 0.8 =0.5+5` `or p=0.3" "(2)` `P(AuuB)=P(A)+P(B)=P(A)+P(B)-P(AuuB)=P(A)+P(B)-P(A)P(B)` `or 0.8=0.5+q-(0.5)q` `or 0.3=q//2` `or q//p=2`
2 Answers 1 viewsCorrect Answer - C `P (bar(AuuB))=1/6` `P(AuuB)=5/6,P(A)=3/4` `P(AuuB)-P(A)+P(B)-P(AnnB)=5/6` `impliesP(B)=5/6-3/4+1/4=1/3` `impliesP(AnnB)=P(A).P(B)=1/4`
2 Answers 1 viewsCorrect Answer - A::D Let `P(E)=eand P(F)=f` `P(EuuF)-P(EnnF)=11/25` `impliese+f-2ef=11/25" "(1)` `P(barEnnbarF)=2/25` `implies(1-e)(1-f)=2/25" "(2)` From (1) and (2), `ef=12/25and e+f=7/5` Solving, we get `e=4/5,f=3/5or e=3/5,f=4/5`
2 Answers 1 viewsCorrect Answer - A::D `(a,d)` `P(AnnB)=a`, `P(A)=a+d`, `P(B)=a+2d`, and `P(AuuB)=a+3d` also `a+d=d` `implies a=0` `implies P(AnnB)=0`, `P(A)=d`, `P(B)=2d` an `P(AuuB)=3d`
2 Answers 1 viewsCorrect Answer - C `(c )` `P(auuB)=P(A)+P(B)-P(AnnB)` ………`(i)` When `A` and `B` are mutually exclusive, then `P(AnnB)=0` `:.0.8=0.5+p` `:.p=0.3` When `A` and `B` are independent `P(AnnB)=P(A)*P(B)` `:.` From `(i)` , `0.8=0.5+q-(0.5)q`...
2 Answers 1 viewsCorrect Answer - D `(d)` Let `P(A)=P(B)=p` (say) `P(B//A)=(P(BnnA))/(P(A))` `:.(0.8)p=P(BnnA)`………..`(i)` `P(AuuB)=p+p-P(AnnB)` `0.6=2p-p(0.8)=(1.2)p` `:.p=(0.6)/(1.2)=(1)/(2)` `:.P(A)=P(B)=(1)/(2)` Now, `P[AnnbarB) uu (barAnnB)]` `=P(A)+P(B)-2P(AnnB)` `=1-2(0.8)(1)/(2)=0.2=(1)/(5)`
2 Answers 1 views