Permutations an...

The no. of 10 letter codes that can be formed using the characters x,y,z,r with the restriction that x appears exactly thrice and y appars exactly twice in each such codes is

A rectangle with sides 2m–1 and 2n–1 is divided into squres of unit length by drawing Parallel lines as shown in the diagram then the no.of rectangles possible with odd side length is _______

The number of seven digit integers with sum of the digits equal to 10 and formed by using the digits 1,2 and 3 only is _______

If a denotes the no. of permutation of x + 2 things taken all at a time, b the no. of permutation of x things taken 11 at a time and c the no. of permutation of x – 11 things taken all at a time such that a = 182bc then the value of x is _______

In how many ways can 15 members of a school sit along a circular table, when the secretary is to sit on side of the principal and the deputy secretary on the other side ?

The total no. of permutations of n(n > 1) different things taken not more than r at a time, when each things may be repeated any no. of times is _______

A car will hold 2 in the front seat and 1 in the rear seat. If among 6 persons 2 can drive, than no. of ways in which the car can be filled is _______

ABCD is a convex quadrilateral. 3,4,5 and 6 points are marked on the sides AB,BC,CD and DA resp. The no.of triangles with vertices on different sides are _______