Answer:
0.625 = 62.5% probability that part B works for one year, given that part A works for one year.
Step-by-step explanation:
We use the conditional probability formula to solve this question. It is

In which
P(B|A) is the probability of event B happening, given that A happened.
is the probability of both A and B happening.
P(A) is the probability of A happening.
The probability that part A works for one year is 0.8 and the probability that part B works for one year is 0.6.
This means that 
The probability that at least one part works for one year is 0.9.
This means that: 
We also have that:

So


Calculate the probability that part B works for one year, given that part A works for one year.

0.625 = 62.5% probability that part B works for one year, given that part A works for one year.
Answer:
2/8 is one-half as much as 1/2
Step-by-step explanation:
Change the denominators to the same number.
2/8 is already okay
1/2=4/8
now
2/8 would be one-half as much as 4/8