Answer:
30:54
Step-by-step explanation:
5:9 x 6 = 30:54
Let

denote the event that an HD is defective, and

the event that a particular HD was produced at facility

.
You are asked to compute



From the definition of conditional probabilities, the first two will require that you first find

. Once you have this, part (c) is trivial.
I'll demonstrate the computation for part (a). Part (b) is nearly identical.
(a)

Presumably, the facility responsible for producing a given HD is independent of whether the HD is defective or not, so

.
Use the law of total probability to determine the value of the denominator:

We know each of the component probabilities because they are given explicitly: 0.015, 0.02, 0.01, and 0.03, respectively. So

and thus

(b) Similarly,

(c)
Answer:

Step-by-step explanation:
we know that
Betsy can clean a/b of the house in an hour
The whole house (100%) correspond to the number 1
so
using proportion
Find out how long will it take her to clean the whole house
