Answer:
Probability distribution for x:

Step-by-step explanation:
We can model the number of defective sets in the group of TV sets (variable x) as a binomial variable, with sample size=3 and probability of success p=2/7≈0.2857.
The probability of k defective sets in the group is:

So, we have this probabilty distribution for x:

The correct answer is choice d.....
You find the lowest common denominator of both fractions, which in this case is 24.
1/6 is equivalent to 4/24 and 1/8 is equivalent to 3/24.
4/24 + 3/24 = 7/24
The correct answer to this would be -3x+8
Change 15/20 to 3/4
Now we have

multiply 6 to 3= 18 ÷ 4 = 4.5
x = 4.5