# Three unbiased coins are tossed once. Find the probability of getting

Question:

Three unbiased coins are tossed once. Find the probability of getting

at most 2 tails or at least 2 heads

Solution:

We know that

Probability of occurrence of an event

$=\frac{\text { Total no. of Desired outcomes }}{\text { Total no.of outcomes }}$

Let $\mathrm{T}$ be tails and $\mathrm{H}$ 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 $=\frac{7}{8}$

Conclusion: Probability of getting at least two heads or at most two tails is $\frac{7}{8}$