Question

Arithmetic Progression, Class X
CBSE​

Answer 1

First term a = -4/3
Common difference d = -1-(-4/3) = -1+4/3 = 1/3
Suppose there are n terms in the given AP. Then, Thus, the given AP contains 18 terms. So, there are two middle terms in the given AP.
The middle terms of the given AP are (18/2)th terms and (18/2+1)th term i.e. 9th term and 10th term.
Sum of the middle most terms of the given AP. =  9th term + 10th term.
Hence, the sum of the middle most terms of the given AP is 3.
Hope it helps you

Answer 2

a=-4/3 d=-1+4/3=1/3 l=a+(n-1)d
13/3=-4/3+(n-1)(1/3)
17/3=(n-1)1/3
17=n-1
So n=18
Middle terms are 9th and 10th
So a(9)=-4/3+8*1/3=4/3
And a(10)=-4/3+9*1/3 =5/3
Sum =4/3+5/3=9/3=3