Final answer:
To find the 12th term of the arithmetic sequence, subtract the 4th term from the 5th term to find the common difference (-2.2). Use the formula an = a1 + (n - 1)d to find the 12th term. The 12th term of the sequence is -5.8.
Step-by-step explanation:
An arithmetic sequence is a sequence of numbers in which the difference between consecutive terms is constant. To find the 12th term of the sequence, we need to find the common difference first. We can do this by subtracting the 5th term from the 4th term:
Common difference (d) = a5 - a4 = 16.2 - 18.4 = -2.2
Now that we know the common difference, we can find the 12th term using the formula:
an = a1 + (n - 1)d
Substituting the known values:
a12 = 18.4 + (12 - 1)(-2.2)
a12 = 18.4 + 11(-2.2)
a12 = 18.4 - 24.2
a12 = -5.8