B I think sorry if I’m wrong on mine it say that’s right
I believe you are missing some information here as the answer to the question as it is written is 4.5
Answer:
(a)

(b)


Step-by-step explanation:
Given

Solving (a): The pmf
This means that we list out the probability of each value of x.
To do this, we simply subtract the current probability value from the next.
So, we have:

The calculation is as follows:





The x values are gotten by considering where the equality sign is in each range.
means 
means 
means 
means 
means 
Solving (b):

This is calculated as:

From the given function


So:



This is calculated as:




If the length is 2ft longer than it’s width
Let’s assume width as X and so the length will be X+2
Perimeter=40ft
Putting the values into a equation, we get,
X+2+X=40
=2X+2=40
=2X=38
=X=19
Therefore
Length =X+2=19+2
=21ft
Width=X=19ft
Area of rectangle =lxb
= 21x19
3992ft
HOPE IT WAS HELPFUL :)