a) We fin the probability in a random selected person between 1.5 min and 5 min.
1 to 9 is a interval of 8 minutes.
1.5 to 5 is a interval of 3.5
[tex]P(1.5<x<5)=\frac{5-1.5}{9-1} = \frac{3.5}{8}=0.4375[/tex]
b) With the formula of Expected Value we can find the time, that is
[tex]E(t) = (a+b)/2 = (9+1)/2 =[/tex]5 minutes
c) The standar desviation of uniform distribution is given by,
[tex]s= \frac{a-b}{\sqrt{n}}[/tex]
[tex]s=\frac{9-1}{\sqrt{12}}[/tex]
[tex]s=2.3094[/tex]
