Basic random variable question - lim of min of a set of RV's

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  1. wanderlust.xx's Avatar
    • TSR Demigod
    • Location: London
    • Posts: 5,086
    Basic random variable question - lim of min of a set of RV's
    Let the independent, identically distributed random variables X_1, X_2, ... ,X_n have common distribution function F(x).

    Denote Z=min(X_1,X_2,...,X_n)

    Question: When the distribution of X_1 is uniform over the interval [0,1], find the limit \displaystyle\lim_{n\to \infty} P\{nZ\leq x\} for x > 0.

    So far, this is what I have:

    f(x) = 1 \implies \ F(x) = \int_0^x f(s) ds = x, \ 0 \leq x \leq 1

    P\{Z\leq x \} = 1-[1-F(x)]^n

    \therefore P\{nZ\leq x \} = P\{Z\leq \frac{x}{n} \}  = 1-[1-F(\frac{x}{n})]^n = 1-\left(1-\frac{x}{n}\right)^n \to \ ?

    Well basically I'm just double checking this is correct. If it is, then would the final term tend to 1? If so, why exactly?
  2. ghostwalker's Avatar
    • Outcast of Imrryr
    • Location: CA13
    Re: Basic random variable question - lim of min of a set of RV's
    (Original post by wanderlust.xx)
    ...
    You may find this helpful:

    http://en.wikipedia.org/wiki/Exponential_function
    Last edited by ghostwalker; 17-05-2012 at 11:00.
  3. wanderlust.xx's Avatar
    • TSR Demigod
    • Location: London
    • Posts: 5,086
    Re: Basic random variable question - lim of min of a set of RV's
    (Original post by ghostwalker)
    You may find this helpful:

    http://en.wikipedia.org/wiki/Exponential_function
    Ah yes of course. Cheers.
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