There are 20 people among whom two are sisters. Find the number of ways in which we can arrange them around a circle so that there is exactly one person between the two sisters ?  Choose the correct choice from the following choices.
A) 18!  B) 2! x 19!  C) 19!  D) 17!  E) None of these
First arrange the two sisters around a circle in such a way that there will be one seat vacant between them. [This can be done in 2! ways since the arrangement is not circular.]   Then, the other 18 people can be arranged on 18 seats in 18! ways.So, total number of ways = 18! x 2! ways   ANSWNone of theseR:None of these
<result>E</result>
There are 20 people among whom two are sisters. Find the number of ways in which we can arrange them around a circle so that there is exactly one person between the two sisters ?