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 exactly two tails. So, desired outputs are TTH, THT, HTT

Total no.of outcomes are 8 and desired outcomes are 3

Therefore, the probability of getting exactly 2 tails

Conclusion: Probability of getting exactly two tails is