At an election meeting 10 speakers are to address the meeting. The only protocol to be observed is that whenever they speak P.M. will speak before M.P., and M.P. will speak before M.L.A. In how many ways can the meeting be addressed ?

Open in App

Solution

Here we select three places for P = P.M.,
Q =M.P., R = M.LA.
Ten speakers can address in 10! ways including the P, Q, R. Now P, Q, R can be arranged amongst themselves in 3! = 6 ways like PQR, PRQ, QRP, QPR, RPQ, RQP Since we want only PQR order, hence we will take $\frac{1}{6}$ th of the total. Hence the required number is $\frac{1}{6}$ $(10!) .$

Suggest Corrections

Similar questions

Q. At an election meeting six speakers have to address the meeting. The President of the party is to speak before the M.L.A. of the constituency. In how many ways can this be done? In how many of these arrangements will the M.L.A. speak just after the speech of the President?

Q. If eight persons are to address a meeting, then the number of ways in which a specified speaker is to speak before another specified speaker is?

Q. Four speakers will address a meeting where speaker

Q

will always speak after

P

. Then, the number of ways in which the order of speakers can be prepared is

Q. Number of ways seven persons can address a meeting such that among three persons A, B and C, A will speak before B and B before C is ___.

A meeting is to be addressed by 5 speakers A, B, C, D, E. In how many ways can the speakers be ordered, if B must not precede A (immediately or otherwise)?

Join BYJU'S Learning Program