perplexus.info :: Probability : Stephen's Book

Stephen's Book (Posted on 2024-06-17)

Stephen is reading a 5000-page book.

What is the probability that the first digit of the page he is on is 1, 2, 3, 4 or 5?

a) obtain an expression.

b) approximate a numerical value.

No Solution Yet Submitted by K Sengupta

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Just counting (spoiler)

Comment 1 of 1

The probability is 5/9 if his page number has 1 or 2 or 3 digits, and 1 if his page number has 4 digits.

So the expression is ((5/9) * 999 + 1*4001)/5000

This evaluates to 4556/5000, which is 91.12%

Posted by Steve Herman on 2024-06-17 07:17:02

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