Answer:
John spent around $53
Step-by-step explanation:
The equation is 3x=160
Since the "x" is already by itself on one side, divide 160 by 3
160÷3=53.333⇒
Now if that's not the way IT CAN ALSO BE:
30x3+70=160! That means John spent $90
Wow!!thats a word from the old english that made it
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%