Answer:
I believe it is a=64; b=2 divided by 10 (I'm sorry if it's wrong I hope you pass)
The exponential distribution is:

where

The probability we want is how likely will a dvd player last more than 8 years, given it has already lasted 5 years
To find this, you use conditional probability.

where A is P(x>8) and B is P(x>5)
To find these probabilities, integrate over the distribution:

Sub into conditional probability formula:

Final Answer: Given a dvd player is more than 5 years old, the probability that it will last another 3 more years is about 54.9%
The square root of 15 is irrational.
The answer is D. Because the deeper you go in the ocean the colder it gets, and it also gets higher salinity.
I think this is what your talking about