I am explaining your question mathematically,


We know the formula of probability is :- possibility=  (Number of favorable outcomes of events / Number of possible outcomes)

suppose :- Number of favorable outcomes of events {P} and Number of possible outcomes {X}

As this as this:- Number of favorable outcomes of events(P):- 10
Number of possible outcomes(X):- 3

Therefore :- possibility= (P/X)

= (10/3)

=30%


With a 30% chance, since a new block is mined every 10 minutes, it is possible to mine about 3 blocks every 10 minutes. And in 10 minutes the chance of having exactly three blocks mined is 30% or (10/3)%.