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atrus_ovis
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Homework Statement
Prob. density function is given below, representing probability of answer in a telephone service center
f(x) = c 2x-1/ 5x
where X is the random variable representing tries (phone calls).
a)find c
b)find the cumulative distribution function
i think i can solve the rest if i get through the first obstacles.
Homework Equations
The sum of a discrete density function from -inf to inf equals 1
The Attempt at a Solution
X is discrete, and the sum from -inf to inf must equal 1.
I sum up from 0 to inf (as negative phone calls don't make sense. is that right to do?) and come up with c=3/4
SUM c 2x+1 /5x , from 0 to inf
=lim, k->inf of SUM (1/3)x , x from 0 to k
=((c/2) * 1-(1/3)inf + 1 )/(2/3) = 1
=>c=4/3
So f is now simplified to 1/3x+1
Is the above method correct? Sadly, i then take the sum from 0 to inf to verify that it equals 1, but it doesn't.
How can i find the cumulative distribution?
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