| A fair coin is tossed 4 times. What is the
probability that the coin landed heads up exactly 3 times? |
By drawing out the possible tosses, we find that
there are four 3 head/1 tail outcomes:
H-H-H-T
T-H-H-H
H-T-H-H
H-H-T-H
Since each of the 4 tosses can be either heads
or tails, we can calculate the number of possible outcomes as follows:
2 
2
2 2 = 16.
We have four 3 head/1 tail outcomes and 16 possible
outcomes, so our probability fraction is 
We can also calculate the probabilities for each
desired outcome:
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Possible Combinations
3 Head/1 Tail
|
Probability of Each Toss
|
Combined Probability
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=  |
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= |
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= |
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= |
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| Probability of
tossing 2 tails on 3 tosses: |
=  |
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Video Lessons and 10 Fully Explained Grand Tests
Large number of solved practice MCQ with explanations. Video Lessons and 10 Fully explained Grand/Full Tests.