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what do you guys think the answer is?

Expert replies
Source: — Problem Solving |

by Stuart@KaplanGMAT » Fri Feb 01, 2008 12:26 am
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.
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thanks but...

by meghamehta15 » Fri Feb 01, 2008 12:50 am
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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by Stuart@KaplanGMAT » Fri Feb 01, 2008 1:23 am
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.
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