Answer:
-197.2
Explanation:
Since it is arithmetic series, first find the difference d between the two know series.
3.8 - 6 = - 2.2
d = -2.2
a = 6
Tn = -29.2
Looking for the n term, use the linear method.
Tn = a+( n - 1)d
Substitute all the parameters
-29.2 = 6+( n - 1 ) -2.2
-29.2 = 6 - 2.2n + 2.2
- 29.2 = 8.2 - 2.2n
-29.2 - 8.2 = - 2.2n
-37.4 = -2.2n
n = 37.4/ 2.2
n = 17 terms.
To Find the exact sum of the arithmetic series, use the sum formula below
Sm = n/2( 2a + (n - 1)d)
Sm = 17/2( 2 × 6 + ( 17 - 1 ) -2.2
Sm = 17/2(12 - 35.2)
Sm = 8.5( - 23.2)
Sm = - 197.2
Therefore, the exact sum of the arithmetic series is -197.2