How many different arrangements can be made out of the letters in the expansion A2 B3 C4, when written in full ?
2! + 3! + 4!
2 ! 3!
None of these
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 !
5 ( 7 ! )
If 4. 6pr = 6 pr + 1, then r is equal to ________.
4
3
2
1
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 )
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
Twelve students compete for a race. The number of ways in which first three places can be taken as ______.
3!
12 . 11.10
12!/3!
12! ___ 3
The number of selections of 2 candidate for a post out of 5 equally qualified candidates.
P ( 5, 2 )
( 5 - 2 ) !
10
The value of n, when np2 = 20 is ________.
6
5
Fifteen girls compete in a race. The first three places can be taken by them in ________.
3 ! ways
12! ways
15 x 14 x 13 ways
42 ways
If npr = 720 ncr, then r is equal to _________.
7
