4) Una urna contiene 18 bolas rojas y 12 bolas blancas. Se sacan 3 bolas de la urna una tras otra. Hallar la probabilidad de que las dos primeras sean rojas y la tercera blanca A) \( 153 / 1055 \) B) \( 15 / 1405 \) C) \( 31 / 1085 \) D) \( 153 / 1015 \)

17. La variable aleatoria continua \( X \) tiene la siguiente función de densidad \( d \) probabilidad: \[ f(x)=\left\{\begin{array}{l}0,25 ; \text { si } 0 \leq x \leq 4 \\ 0 \text { do }\end{array}\right. \] \[ \begin{array}{l}\text { dontrario }\end{array} \]

In a town, the number of electric power failures occurs randomly with an average of one failure every 4 months. What is the variance associated with the number of failures over six consecutive months?

The number of births in a hospital follows a Poisson distribution with an average number of 1 birth per hour. What is the probability that there will be at least one birth within the next 2 hours? \( \frac{0.8647}{0.6321} \) 0.1353

5. Lança-se uma moeda e verifica-se se a face voltada para cima é cara ou coroa. Indique, na forma de fraçào, de nú- mero decimal e de porcentagem, a probabilidade de o resultado ser: a) cara; b) coroa. Lança-se um dado comum e observa-se o número de pontos de sua face superior. Calcule a probabilidade de o número obtido ser: a) par;

The number of births in a hospital follows a Poisson distribution with an average number of 1 birth per hour. What is the probability that there will be no birth within the next 2 hours? 1.00 0.135 0.368 0.250