The probability of mining a new block every 10 minutes is about 1/10 or 10% on average.

 If each block has a 10% chance of being mined, then the probability of mining three blocks is:

 (10% * 10% * 10%) = 0.1 * 0.1 * 0.1 = 0.001

 Or 0.1%, ie 1/1000. So the probability of mining three blocks in the next 10 minutes is about 0.1% or 1/1000.

Otherwise,,,

Since there is a binomial probability for each event (yes or no), the probability will be the average position of the numbers.

 Given its value, the binomial probability for each event will be 1/2.

  Then the probabilities for the first three events would be:

 (1/2) * (1/2) * (1/2) = 1/8