By all fair means

Probability Level 3

An unbiased coin is tossed three times. It is known that the coin shows a head in the first throw. What is the probability that the coin will show heads in at least two tosses?

1 4 \frac{1}{4} None of the given options. 3 4 \frac{3}{4} 1 2 \frac{1}{2}

Abhay Tiwari by Abhay Tiwari , 28, India

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1 solution

Ashish Menon
Jun 6, 2016

The possibilities for showing atleast two heads is H H H , H L H HHH , HLH and H H L HHL . Since first throw is always a head, the number of possibilities is 2 2 = 4 2^2 = 4 .

So, the probability for getting atleast two heads is 3 4 \color{#3D99F6}{\boxed{\dfrac{3}{4}}} .

2 Helpful 0 Interesting 0 Brilliant 0 Confused

Absolutely correct. :)

Abhay Tiwari - 5 years ago

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