There are four letter boxes in a post office. In how many ways can a man post 8 distinct letters.
8 x 8
84
4 8
8 p 4
If 4. 6pr = 6 pr + 1, then r is equal to ________.
4
3
2
1
Six identical coins are arranged in a row. The number of ways in which the number of tails is equal to number of heads is _______.
20
120
9
40
If npr = 720 ncr, then r is equal to _________.
6
5
7
The number of selections of 2 candidate for a post out of 5 equally qualified candidates.
P ( 5, 2 )
5 !
( 5 - 2 ) !
10
The number of different four digit numbers that canbe formed with the digits 2, 3, 4, 5, 7 using each digit only once is _______.
4 !
4 ( 4 ! )
5 ( 7 ! )
The number of handshakes that can be exchanged among a party of 12 students if every student strikes hands once with every other student is _________.
P ( 12, 2 )
P ( 12, 10 )
C ( 12, 2 )
None of these
How many 10 digits number can be written by using the digits 1 and 2.
10 C1 +9 C2
2 10
10C1
10 !
The number of ways in which 9 studnets can be equally distributed among 3 sections is ________.
9!
In how many ways can 7 toys be given away to 3 children when each child is eligible for all the toys ?
3570
4350
2187
2426
