Question

Find the $20th$ term from the last term of the AP $3,8,13,....253.$

• A. $156$
  
• B. $180$
• C. $158$
• D. $188$

Answer 1

The correct option is C $158$

The AP is $3,8,13,....,253$
Its first term $=3$ and the common difference $=5$
The AP in the reverse order will have the first term $=253$ and the common difference $=-5$
The $20th$ term from the end of the given AP $=$ The $20th$ term of the AP in the reverse order$=a+19d$
$=253+19\times (-5)=253-95=158$