Question

If Roll no 31 sits immediately before Roll no 23, then who sits immediately after 24?

• A. 27
• B. 32
• C. 29
• D. 30

Answer 1

The correct option is D 30

31 is sitting immediately before 23
1: 24 on $5^{th}$ Bench and 27 on $6^{th}$ Bench
$\frac{31}{1}\frac{23}{2}\frac{}{3}\frac{}{4}\frac{24}{5}\frac{27}{6}\frac{}{7}\frac{}{8}\frac{}{9}\frac{}{10}$
This case is not the best case because we have to seat 25 and 32 as far as possible is at extreme ends.
Case 2: 24 on $6^{th}$ Bench and 27 on $5^{th}$ Bench
$\frac{25}{1}\frac{31}{2}\frac{23}{3}\frac{30}{4}\frac{27}{5}\frac{}{7}\frac{}{8}\frac{}{9}\frac{32}{10}$
26 and 28 sit on consecutive seats is either on $7^{th}$ and $8^{th}$ Bench or on $8^{th}$ and $9^{th}$ Bench and 29 can sit on $7^{th},8^{th}or{9}^{th}$
Bench
Therefore 30 sits on $4^{th}$ Bench