In a 12 - storey house ten people enter a lift cabin. It is known that they will left in groups of 2, 3 and 5 people at different storeys. The number of ways they can do so if the lift does not stop to the second storey is
A.
78
B.
112
C.
720
D.
132
Answer :
720
Solution :
Leaving the ground floor and second floor, their are 10 floors in which three groups of
people can left the lift cabin in $$^{10}{P_3}$$ ways, i.e. 720 ways.
Releted MCQ Question on Algebra >> Permutation and Combination
Releted Question 1
$$^n{C_{r - 1}} = 36,{\,^n}{C_r} = 84$$ and $$^n{C_{r + 1}} = 126,$$ then $$r$$ is:
Ten different letters of an alphabet are given. Words with five letters are formed from these given letters. Then the number of words which have at least one letter repeated are
Eight chairs are numbered 1 to 8. Two women and three men wish to occupy one chair each. First the women choose the chairs from amongst the chairs marked 1 to 4 ; and then the men select the chairs from amongst the remaining. The number of possible arrangements is