C because a number cube has six sides and there are six residents. So you have chosen correctly by picking C. You can say you decided that due to the number of residents being the same number as sides on a number cube that it would make sense to roll a number cube to predict the randomly chosen resident.
well, rational = fractional, namely something you can write as a fraction, well, anything between -1 and -2 is just less than -1 so

I got 20.
I may have done it wrong so maybe wait until others have answered.
Answer:
The explicit form f(n) is 
Step-by-step explanation:
A sequence is arithmetic if the difference between each consecutive terms is a constant.
The explicit formula of an arithmetic sequence is:

Where d is the common difference, a1 is the first term of the sequence and an is the nth term.
In order to obtain the common difference, you have to subtract two consecutive terms:
For the first and second terms:
2a+1 - a = a+1
For the second and third terms:
3a+2 - (2a+1)=
Applying the distributive property:
3a+2-2a-1= a+1
Notice that the difference of any two consecutive terms is the same. Therefore:
d=a+1
Also, a1=a (The first term)
Replacing in the explicit formula:

I’m not sure what the negative fours are at the end of your problem are for, but the slope of the line passing through those points is 4.
The line itself is y = 4x - 11