We know that,

Probability of occurrence of an event

Let T be tails and H be heads

Total possible outcomes = TTT, TTH, THT, HTT, THH, HTH, HHT, HHH

Desired outcomes are at least two tails. So, the desired outputs are

TTH, THT, HTT, TTT

Total no.of outcomes are 8 and desired outcomes are 4

Therefore, the probability of getting at least 2 tails

Conclusion: Probability of getting at least two tails is