Question

Time spent discussing material with students during office hours follow an exponential
distribution with mean of 15 minutes.
a) Find the probability that a student spends less than 10 minutes discussing material in
office hours.
b) Find the probability that a student spends more than 3 minutes discussing material
during office hours.
please and thanks been puzzling for me

Answer 1

let me see if i can remember this correctly. i think we put
\[\lambda =\frac{1}{15}\] and use
\[P(X>s)=e^{-\lambda s}\] and
\[P(X<s)=1-e^{\lambda s}\] does that look familiar?

Answer 2

sorry last one should be
\[P(X<s)=1-e^{-\lambda s}\]

Answer 3

so first one would be
\[P(X<10)=1-e^{-\frac{10}{15}}=1-e^{-\frac{2}{3}}=0.48658288\] rounded

Answer 4

similarly
\[P(X>3)=e^{-\frac{3}{15}}=e^{\frac{-1}{5}}=0.8187\]

Answer 5

thanks , yes that is the correct value (1/15) i do believe your on the right track

Answer 6

just looked it up and they are right unless i really missed my guess

Answer 7

thanks your correct, its concistent with my notes...you wouldnt possibly know how to the previous one i posted would you?

Answer 8

i will look