Question

3. Se X denota o número de caras na jogada de 4 moedas, determine (a) P
[X=3). (b) P[X<2). (c) P(X <2), (d) P[1<x<3).​

Answer 1

Resposta:

(a) P[X=3) = C4,3 * (1/2)³ * (1/2)=4/16=1/4

(b) P[X<2)=P[X=0]+P[X=1] =(1/2)^4 + C4,1 * (1/2)*(1/2)³ =1/16+ 4/16 =5/16

(c) P(X <2)=P[X=0]+P[X=1] =(1/2)^4 + C4,1 * (1/2)*(1/2)³ =1/16+ 4/16 =5/16

(d) P[1<x<3]=P(X=2] =C4,2 *(1/2)²*(1/2)² = 6/16=3/8

===> c) repetiu b)