Answer:
The correct answer option is 36.
Step-by-step explanation:
We know that,
the sum of the first n terms of an Arithmetic Sequence is given by:
[tex]S_n=\frac{n(a_1+a_n)}{2}[/tex]
where [tex]n[/tex] is the number of terms,
[tex]a_1[/tex] is the first term of the sequence; and
[tex]a_ n[/tex]is the first term of the sequence.
So for [tex]a_n=(19-4n)[/tex],
[tex]a_1=19-4(1)=15\\\\a_4=19-4(4)=3[/tex]
Putting these values in the formula to get:
[tex]S_4=\frac{4(15+3)}{2}[/tex]
[tex]S_4=\frac{72}{2} \\\\S_4=36[/tex]
Therefore, the 4th term of the given sequence is 36.
