Ten different letters of an alphabet are given. Words with five letters are formed from these given letters. Then the numbers of words which have at least one letter repeated are
A
69760
B
30240
C
99748
D
none of these
2
IIT-JEE 1979
MCQ (Single Correct Answer)
$${}^n{C_{r - 1}} = 36,{}^n{C_r} = 84\,\,and\,\,{}^n{C_{r + 1}} = 126$$, then r is :
A
1
B
2
C
3
D
None of these.
Questions Asked from Permutations and Combinations
On those following papers in MCQ (Single Correct Answer)
Number in Brackets after Paper Indicates No. of Questions
