To solve this question we will use the following expression to compute the theoretical probability:
[tex]\frac{\text{favorable cases}}{total\text{ cases}}\text{.}[/tex]Now, recall that the possible outcomes of rolling a die are 1, 2, 3, 4, 5, and 6. Therefore the probability of obtaining no 6 in each rolling is:
[tex]\frac{5}{6}\text{.}[/tex]Then, the probability of obtaining no 6's in four rollings is:
[tex]\frac{5}{6}\times\frac{5}{6}\times\frac{5}{6}\times\frac{5}{6}\text{.}[/tex]Simplifying the above product we get:
[tex]\frac{5^4}{6^4}=\frac{625}{1296}\text{.}[/tex]Answer:
[tex]\frac{625}{1296}\text{.}[/tex]