Question

In how many ways $9$ mathematics papers can be arranged, so that the best and the worst paper are always together

• A. $8!2!$
• B. $7!2!$
• C. $8!3!$
• D. None of these

Answer 1

The correct option is A $8!2!$

There are $9$ math papers. Given that best and worst must come together.

So, consider best and worst together as one object

which means number of object $=8$

we can arrange these $8$ in $8!$ ways

we can interchange best and worst in $2!$ ways

Number of ways $=8!2!$