Question

Question 1 (iv)
Fill in the blanks in the following table, given that a is the first term, d the common difference and $a_n$ the $n^{th}$ term of the A.P.
$\begin{array}{ccccc}& a& d& n& a_n\\ \left(iv\right)& -18.9& 2.5& \dots \dots & 3.6\end{array}$

Answer 1

(iv) $a=-18.9,d=2.5,a_n=3.6,n=$?
We know that,
$a_n=a+(n-1)d3.6=-18.9+(n-1)2.53.6+18.9=(n-1)2.522.5=(n-1)2.5(n-1)=\frac{22.5}{2.5}n-1=9n=10$