00:01
The probability density function for the time to failure of an electronic component is shown here.
00:09
For part a, we want to determine the probability that the component lasts more than 3 ,000 hours before failure.
00:25
This is equal to the integral from 3 ,000 to infinity of our probability density function.
00:46
This is equal to e to minus x over 1 ,000, evaluated from 3 ,000 to infinity.
00:57
And there should be a minus in front.
01:03
And this is equal to e to the minus 3, minus 0, or approximately 0498.
01:19
For part b, we are asked for the probability that the component fails in the interval from 1 ,000 to 2 ,000 hours.
02:04
This is equal to e to the minus 1, minus e to the minus 2, or approximately 0 .2325.
02:17
For part c, we are asked to find the probability that the component fails before 1 ,000 hours.
02:29
So that is the probability that x is less than 1 ,000.
03:04
This is equal to 1 minus e to minus 1, which is approximately .6321...