The cdf of checkout duration X for a book on a 2hour reserve
The cdf of checkout duration X for a book on a 2-hour reserve at a college library is given by: F(x) = {0 x lt 0 x^2/4 0 lessthanorequalto 2 1 2 lessthanorequalto x Use this cdf to compute the following: P(X lessthanorequalto 1) P(.5 lessthanorequalto X lessthanorequalto 1) P(X gt.5) The median checkout duration mu Fprime(x) to obmin the density function f(x)
Solution
(a)
P(X 1) = F(1)
= (1/4) x2 dx --- integrate from 0 to 1 [formula :- xn = xn+1/ n+1]
= x3/12
= 1 /12 - 0 /12 = 1/12
b)
P(.5 X 1) = F(1) - F(.5)
we already know that F(1) = 1/12
Now F(.5) = (1/4) x2 dx --- integrate from 0 to .5
= (.5)3 /12 = 0.125/12
Now substitute in the given relation then
F(3) - F(.5) = 1/12 - 0.125/12 = 0.0729
c)
P( x > .5) = 1 - P(x .5) = F(.5)
= (1/4) x2 dx --- integrate from 0 to .5
= (.5)3 / 12 = 0.125/12
d)
(1/4) x2 dx from 0 to M is 0.5
M3/12 = 0.5 ,
where M =median
M3 = (12)(0.5) = 6
M =1.817
e)
F(x) = x2/4 , 0 x 2
F\'(x) = 2x/4 , 0 x 2
f(x) = (2/4) x , 0 x 2
