1-The length of life of an electronic component has an exponential probability density function with mean 1000 hours.What is the median number of hours the life of the electronic component will last?

544 hours 45 minutes and 37 second

693 hours 8 minutes and 49 seconds

500 hours 30 minutes and 15 second

1039 hours 43 minutes and 14 second

2-The joint density function of X and Y is given by

f(x, y) =xe^-(x+y)x > 0,y > 0

0otherwise

What is E(x)?

5e^-2

2e^-2

e^-2

4e^-2