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    • Thread Starter

    a televison repair company uses a particular spare part at a rate of four per week. Assumming that requests for this spare part occur at random. find

    a) exactly six are used in one week
    b) at least ten are used in a 2 week period
    c)exactly six are used in each three consective week

    the manager decides to replenish the stock of this spare part to a constant level n at the start of each week.

    d) find the value of n such that , on average the stock will be insufficent no more than once in a 52 week year

    I have done a b c , there easy its just part d) the answer to d is 9 , dont know how

    thanks for any help

    OK - what you need to do for part (d) is to find a value of n such that P(X > n) = 1/52, where X is the number of parts used.

    Rearrange that to P(X <= n ) = 51/52 = 0.9808

    Now, look up in the cumulative Poisson table with lamba=4 the first value that gives us a probability of more than 0.9808. This is 9. So n=9.

    Hope this helps.
    • Thread Starter

    thanks for ur help
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Updated: June 14, 2005
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