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Random x Random (Posted on 2009-08-17) Difficulty: 4 of 5
Let x and y each be random real numbers chosen from the uniform interval (0,1). Call the product of these numbers z.

1) Find the probability that z is in the interval (.1,.2)

2) Find the probability that z is any decimal whose first digit when written in scientific notation is a 1.

Bonus) Find the full probability distribution of the first digit of z.

Note: Give all answers as exact numbers in closed form.

No Solution Yet Submitted by Jer    
Rating: 4.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
Puzzle Thoughts Comment 2 of 2 |
(1) .1916290732
(2) .2413481689
(3)The required probability distribution is as follows:
1 + d * ln(d) - (d+1) * ln(d+1)) / 9 + 10 * ln(10) / 81


Edited on February 23, 2024, 11:58 pm
  Posted by K Sengupta on 2024-02-23 23:54:50

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