Answer:
6:12
Step-by-step explanation:
Add 1+2=3
18/3=6
6x1=6
6x2=12
Out it back in the ratio
6:12
For eight loop, multiply it by 3 to get the whole length of loop
8 x 3 = 24 inches
Since 12 inches is equivalent to 1 feet, convert that
24 inches * (1 feet / 12 inches) = 2 feet
Let sister be s. Matthew, M
Matthew is 7years older than twice the age of his sister
M = 7 + 2s
13 = 7 + 2s. 7 crosses the equality to other side and becomes -7
13 - 7 = 2s
6 = 2s Divide both sides by 2
6/2 = 2s/2
3 = s
Sister is 3 years old.
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%