For a given $A.P.$,$S_{10} = 50$ and $a = 0.5$. Then,$d = \ldots \ldots \ldots . .$

Find the sum of those integers from $1$ to $500$ which are multiples of $2$ or $5$.

Which of the following matchings is true for Part $I$ and Part $II$?

Part $I$	Part $II$
$1$. Sixth term of the $A.P.$ $1, 3, 5, 7, \ldots$	$a$. $105$
$2$. Eleventh term of the $A.P.$ $3, 6, 9, 12, \ldots$	$b$. $11$
$3$. Sixteenth term of the $A.P.$ $4, 6, 8, 10, \ldots$	$c$. $33$
$4$. Twenty-first term of the $A.P.$ $5, 10, 15, 20, \ldots$	$d$. $34$

The ratio of the sums of first $n$ terms of two $A.P.s$ is $(7n + 1) : (4n + 27)$. Find the ratio of their $m^{th}$ terms.

The production of a $TV$ factory increases equally every year. Its production in the $3^{rd}$ year was $600 \, TV$ and its production in the $7^{th}$ year was $700 \, TV$. Find the production in the $1^{st}$ year,in the $10^{th}$ year,and the total production in $7$ years.

If the $n$th terms of the two $APs$: $9, 7, 5, \ldots$ and $24, 21, 18, \ldots$ are the same,find the value of $n$. Also,find that term.