The answer you have is good. You don't need to change anything.
Ummm i don't know what the pmf would be but the probability of grabbing a blue sock would be 10 out of 100...
Answer:
k = 11
Step-by-step explanation:
Given the points are collinear then the slopes between consecutive points are equal.
Using the slope formula
m = 
with (x₁, y₁ ) = (5, 1) and (x₂, y₂ ) = (1, - 1)
m =
=
= 
Repeat with another 2 points and equate to 
with (x₁, y₁ ) = (1, - 1) and (x₂, y₂ ) = (k, 4)
m =
, then
=
( cross- multiply )
k - 1 = 10 ( add 1 to both sides )
k = 11
Scale : 1 inch = 30 miles
So, the ratio between the distance on the map and the real distance is 1:30
When a quantity increase/decrease in a ratio, the other one increase/decrease respectively.
Call the miles we have to go : x
1:30 = 4.5:x
(1x4.5):(30x4.5) = 4.5 : x
4.5 : 135 = 4.5 : x
So, x = 135 => We have to go 135 miles to get to the place we want to go.