Paper 7 October/November 2005 MATHEMATICH (9709/7) A Levels
لطفا برای اطمینان از عملکرد و تجربه بهتر از مرورگرهای مدرن و به روز مانند کروم یا فایرفاکس استفاده کنید.

A book contains 40000 words. For each word, the probability that it is printed wrongly is 0.0001 and these errors occur independently. The number of words printed wrongly in the book is represented by the random variable $X$.
a) State the exact distribution of $X$, including the values of any parameters.
b) State an approximate distribution for $X$, including the values of any parameters, and explain why this approximate distribution is appropriate.
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