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A fair coin is flipped 4 times, what is the probability of obtaining at least one head in the first two tosses?

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closed as off-topic by Sycorax, Matthew Drury, Juho Kokkala, Tim, kjetil b halvorsen Feb 28 '17 at 12:56

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Self-study questions (including textbook exercises, old exam papers, and homework) that seek to understand the concepts are welcome, but those that demand a solution need to indicate clearly at what step help or advice are needed. For help writing a good self-study question, please visit the meta pages." – Sycorax, Matthew Drury, Juho Kokkala, Tim, kjetil b halvorsen
If this question can be reworded to fit the rules in the help center, please edit the question.

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Assuming the coin is fair, the first two tosses can be TT, TH, HT, or HH with equal probability for each pair. The last three pairs (three of the four) match your desired first two flips, and the last two flips do not matter because each pair can have the same last two flips. So the probability of obtaining at least one head in the first two of four tosses is $3/4$.

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    $\begingroup$ Please take a look at stats.stackexchange.com/tags/self-study/info (or do you think this is not such a question?) $\endgroup$ – Juho Kokkala Feb 28 '17 at 6:25
  • $\begingroup$ Also, if a fair coin had been tossed and landed heads four times in a row, the odds of getting a heads in the next two flips is still $3/4$. The preceding flips don't matter either. $\endgroup$ – Tavrock Feb 28 '17 at 6:30
  • $\begingroup$ I agree that the question should be tagged as self-study. $\endgroup$ – Travis Feb 28 '17 at 6:31

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