Answer:
4.4722
Step-by-step explanation:
The following table shows the 36 elements of the sample space of the experiment
![\left[\begin{array}{cccccccc}&1&2&3&4&5&6\\--&--&--&--&--&--&--\\1\;|&1&2&3&4&5&6\\2\;|&2&2&3&4&5&6\\3\;|&3&3&3&4&5&6\\4\;|&4&4&4&4&5&6\\5\;|&5&5&5&5&5&6\\6\;|&6&6&6&6&6&6\end{array}\right]](https://tex.z-dn.net/?f=%5Cleft%5B%5Cbegin%7Barray%7D%7Bcccccccc%7D%261%262%263%264%265%266%5C%5C--%26--%26--%26--%26--%26--%26--%5C%5C1%5C%3B%7C%261%262%263%264%265%266%5C%5C2%5C%3B%7C%262%262%263%264%265%266%5C%5C3%5C%3B%7C%263%263%263%264%265%266%5C%5C4%5C%3B%7C%264%264%264%264%265%266%5C%5C5%5C%3B%7C%265%265%265%265%265%266%5C%5C6%5C%3B%7C%266%266%266%266%266%266%5Cend%7Barray%7D%5Cright%5D)
From this table we can compute the probabilities
:
P(X = 1) = 1/36
P(X = 2) = 3/36
P(X = 3) = 5/36
P(X = 4) = 7/36
P(X = 5) = 9/36
P(X = 6) = 11/36
So the expected value equals
1P(X=1)+2P(X=2)+3P(X=3)+4P(X=4)+5P(X=5)+6P(X=6) =
= 1/36 + 6/36 + 15/36 + 28/36 + 45/36 + 66/36 = 161/36 =
4.4722
Hello there is a solution :
Answer: 4.6 horas.
Step-by-step explanation:
Podemos calcular el tiempo necesario por una llave:
si sabemos que se llena en 8 horas con 4 llaves, entonces una sola llave va a tardar 4 veces 8 horas en llenar el tinaco, es decir, una sola llave tarda:
4*8h = 32 horas
ahora, si usamos 7 llaves, el tiempo necesario va a ser un septimo de eso:
(32 h por llave)/(7 llaves) = 32/7 horas = 4.6 horas.
