See the answer to your other question about the distribution of the number

of times a 5 will come up.

Now 600 times is a large number of rolls so we may as well use the normal

approximation to the binaomial distribution, in this case it will have mean:

and standard deviation:

So you would expect the number of 5's to be , where

the value of is chossen by you depending on what confidence you want

that the actual number lies in the interval, often a value of is used.

RonL