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what do you guys think the answer is?
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meghamehta15
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2. A fair coin is tossed 5 times. What is the probability of getting at least three heads on consecutive tosses?
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Stuart@KaplanGMAT
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Exactly 3 consecutive heads out of 5 tosses:
HHHTT
HHHTH
THHHT
TTHHH
HTHHH
Exactly 4 consecutive heads out of 5 tosses:
HHHHT
THHHH
Exactly 5 consecutive heads out of 5 tosses:
HHHHH
That's 8 desired outcomes out of 2^5 possibilities, so 8/32 or 1/4.
HHHTT
HHHTH
THHHT
TTHHH
HTHHH
Exactly 4 consecutive heads out of 5 tosses:
HHHHT
THHHH
Exactly 5 consecutive heads out of 5 tosses:
HHHHH
That's 8 desired outcomes out of 2^5 possibilities, so 8/32 or 1/4.
Stuart Kovinsky | Kaplan GMAT Faculty | Toronto
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meghamehta15
- Junior | Next Rank: 30 Posts
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thank you so much for your answer, but I was wondering if you know of a way to answer this question without having to list down the various combinations? Is there a formula?
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Stuart@KaplanGMAT
- GMAT Instructor
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I'm sure we could figure one out, but because of the "consecutive" part it's going to be more work than just counting them.
Stuart Kovinsky | Kaplan GMAT Faculty | Toronto
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