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    A marina hires out boats on a daily basis. The mean number of boats hired per day is 15. Using the normal approximation for a poisson distribution, find, for a period of 100 days
    a) how often 5 or fewer boats are hired
    b) how often exactly 10 boats are hired
    c) on how many days they will have turn customers away if the marina owns 20 boats.

    I cant do this question at all. I've tried it many times, im not sure whether i should use the 15 or multiply the 15 by 100 first before applying the normal approximation. And after I do this how do I attempt the question? :confused:
    I would really appreaciate it if someone could guide me in the right direction
    bdw The answer for part a) is 1 day b) 4 or 5 days and part c) 8 days- im completly cluless on where these have come from

    Thanks in advance x
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    Use the normal dist N(15,15).
    Work out the relevant probabilities (don't forget the continuity correction!)...and then multiply by 100. So your answer can be interpreted as a percentage.
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    (Original post by vc94)
    Use the normal dist N(15,15).
    Work out the relevant probabilities (don't forget the continuity correction!)...and then multiply by 100. So your answer can be interpreted as a percentage.
    Hey thanks for replying!
    Ok, so when I do what you told me to for part a) I get 0.62.....so how do I convert this to 1 day which is the answer??
    Thanks again
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    a) from Po(15), P(X<=5) becomes P(X<= 5.5) from the normal distribution (15,15) ..which gives 0.007086.
    Multiply by 100 gives 0.7 which is approx 1.
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    (Original post by vc94)
    a) from Po(15), P(X<=5) becomes P(X<= 5.5) from the normal distribution (15,15) ..which gives 0.007086.
    Multiply by 100 gives 0.7 which is approx 1.
    oh I see noww..thankyou so much!!.........one last question if you dont mind...i'm really sorry for bugging you like this but for part c) do I do the same thing using the probability P(x>= 20) or do I use p(x>15) because that is the average boats hired per day?....or is there something else which i'm missing
    Thankss
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    c) customers are turned away when X>=21
 
 
 
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Updated: March 31, 2011
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