Answer : 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 heads or at most two tails. So, desired outputs are TTH, THT, HTT, THH, HTH, HHT, HHH
Total no.of outcomes are 8 and desired outcomes are 7
Probability of getting at most 2 tails or at least 2 heads
Conclusion: Probability of getting at least two heads or at most two tails is 7/8