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
I got the same thing.
To find the probability of having exactly three blocks mined, I multiplied the probability of a single block being mined three times, that is, 1/10 * 1/10 * 1/10 = 1/1000
The chance of having exactly three blocks mined in 10 minutes is 0.001