1. Alice rolls an ordinary six-sided die 8 times in succession, and the numbers are recorded (in order). How many possible outcome sequences contain exactly two occurrences of "6" Briefly explain your answer.(adsbygoogle = window.adsbygoogle || []).push({});

2.Bob tosses a coin 20 times and gets 13 heads and 7 tails. In how many ways can these tosses result in exactly three (non-empty) blocks of consecutive heads? For example, HHHTTHHHHHHHHHTTTHTT has three blocks of consecutive heads. Show all steps of your solution. (Hint: Think of distributing apples and oranges to children such that each child gets at least one apple.)

any help is appreciated. thanks in advance

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# Permutation/combination problems

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