what is the probability that the next random number will equal current one?

Question

if i do this in a worksheet:

=RAND()

i also specified that i want only 2 decimal places

and for example let's say that rand() = 0.07

what is the probability that when i call this function again i will get 0.07 ??

i know that ideally if we assume 100% randomness, the answer would be 1/ (10 * 10) because there are only 100 possible combinations, but what would it be according to the way excel generates a random number?

Answer 1

The random number generator in Excel is pretty good these days. You're going to get really close to it being a 1 in 100 chance. 1 in 101 if you allow 0.0 and 1.0.

Article about the number generator: http://support.microsoft.com/kb/828795

Answer 2

If the random function is uniform, then the probability is 1/100. That's usually what non-mathematicians expect when they specify "random".