The time to failure of a cathode ray tube has the following

The time to failure of a cathode ray tube has the following probability density function with a

mean failure rate 1/ = 1000:

f(t) = { e^-t t >= 0

Assume the cathode ray tube was functioning after 100 working hours. Find the probability,

that the cathode ray tube is still functioning after 300 working hours.

Solution

Time to failure T is exponential with parameter lemda = 0.001

P(t>300/t>100) =e^-3/e^-1

= 1/e^2

= 0.1353