Question

Find the sum of first $16$ terms of the $A.P.1,1.5,2,2.5,........$

Answer 1

$1,1.5,2,2.5,............$

$a=1d=1.5-1=0.5n=16$

sum $=\frac{n}{2}(2a+(n-1\left)d\right)$

$=8\left(2\right(1)+15(0.5\left)\right)8(2+7.5)=9.5\times 8=76.0$