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 March 4th, 2013, 04:11 PM #1 Newbie   Joined: Feb 2013 Posts: 16 Thanks: 0 PDF - probability density functions The probability that a cell drawn at random from a large population has divided at time $t$ greater or equal to 10 (minutes) is $p(t)= Re^{-R(t-10)}$ where $R > 0$ is some constant. (We assume that cells never divide before time t=10 min.) (a) find the mean time for division In pdfs, the area of the probability is equal to one. The mean is equal to the $\int\limits_{10}^\infty p(t)= Re^{-R(t-10)} *t$ After integrating by parts I get the mean time being 11. This is however not the right answer. I found R to be 1, as it is the normalization constant found by finding the area of $p(t)$ and solving for R.
 March 4th, 2013, 05:47 PM #2 Senior Member   Joined: Feb 2013 Posts: 281 Thanks: 0 Re: PDF - probability density functions R = 1. Mean time = 11. You are right.
 March 4th, 2013, 07:48 PM #3 Newbie   Joined: Feb 2013 Posts: 16 Thanks: 0 Re: PDF - probability density functions There must be an error in the online marking system.

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