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1. Three unbiased coins are tossed. What is the probability of getting at least 2 heads?

A. $\frac{1}{4}$

B. $\frac{1}{2}$

C. $\frac{1}{3}$

D. $\frac{1}{8}$

Solution:

Here S = {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH}
Let E = event of getting at least two heads = {THH, HTH, HHT, HHH}

∴ P (E) = \frac{n (E)}{n (S)} = \frac{4}{8} = \frac{1}{2}

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