Answer:
<h2>
<em><u>B. 20% because he only got 400 back</u></em><em><u> </u></em></h2>
<em>Pls</em><em> </em><em>Mark</em><em> </em><em>me</em><em> </em><em>as</em><em> </em><em>brainliest</em><em> </em>
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%
Answer: b=5
Step-by-step explanation:
7(b+2)=49
7b + 14= 49
7b = 49-14
7b= 35
b=35/7
b=5