## Practice Final A7 |
Lilyhui |
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For the question I approached it by using the recursive equation E[X]=4(E[X]+1). The second E[X] is suppose to have a subscript of x-1. The answer is 84 for the third time the die lands on 1 |

arpanshah: March 19, 2015, 7:07 p.m. |
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How exactly would the steps for this one be written out? Thanks! |

Lilyhui: March 19, 2015, 7:24 p.m. |
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Eqn is E[X]=1/p *(E[X]+1). Since it averages 4 rolls to land a 1, p=1/4 thus giving you the eqn E[X]=4(E[X]+1). Again the second E[X] is suppose to have a subscript of x-1(Cant find a way to type it out). From here you would start with E[X1]=4 and continue to plug that into the eqn until you 1 three times in a row |

weisbart: March 20, 2015, 1:25 a.m. |
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You can also do it directly by considering the first few possibilities. What are the false starts that you need to consider? |