Sir
chetan2u please introduce light in my darkened mind
My reasoning was as follows:
If we arrange upper deck the lower one would be arranged automatically and vice versa
We have got 15 people in the upper deck and 10 in lower, so they have seated there and we cant move them by force
Now we are left to arrange 85 people
There is no point which deck we arrange
Upper deck: arranging 85 people on 40 seats: 85!/40!45!
Lower deck: arrangind 85 people on 45 seats: 85!/45!40!
IMO Ans:
BI was concerned after reading EgmatQuantExpert's replay
Actually answer depends on what has been asked..
then \(\frac{85!}{40!45!}\) is correct.
You have shifted 15 and 10 at respective decks and can put remaining 85 in \(\frac{85!}{40!45!}\) ways.
After distributing them in groups of 50 and 60, these 50 and 60 can be arranged in 50! and 60! ways and then answer becomes \(\frac{85!}{40!45!}*50!*60!\)