Permutations and Combinations

 $A\ code\ word\ of\ length\ 4\ consists\ of\ two\ distinct\ consonent\ in\ the\ English\ alphabet\ followed\ by\ two\ digits\ from\ 1\ to\ 9\ with\ repetition\ allowed\ in\ digits.\ If\ the\ number\ of\ code\ words\ so\ formed\ ending\ with\ an\ even\ digit\ is\ 432\times k,\ then\ the\ value\ of\ k\ is$  

• 7

• 5

• 49

• 35

The number of 6-digit numbers, all digits of which are odd is-------------------

• $5^6$

• $6^5$

• $9_{P_6}$

• $6!$

How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated

• 540

• 405

• 504

• 450

 $Evaluate\ 2!\ +4!$  

•  $6!$  

• 6

• 25

• 26

 $Find\ \ \frac{n!}{\left(n-r\right)!},\ n=5,r=2$  

• 15

• 20

•  $\left(\frac{5}{3}\right)!$  

•  $\frac{5}{3}$  

The number of different four digit numbers that can be formed with the digits 2,3,4,7 and using digit only once is

• 24

• 42

• 168

• 12

 $If\ 8_{P_r}=336,\ find\ r$  

• r=4

• r=7

• r=2

• r=3

How many words ( with or without meaning) can be formed from the letters of the word 'AGAIN'?

• 30

• 50

• 60

• 120

Eight children are to be seated on a bench, how many arrangements are possible if the youngest child sits in a corner?

• 10080

• 10060

• 10040

• 10020

 $If\ 15_{P_r}=2730,\ then\ 5_{P_{r\ }}is$  

• 3

• 30

• 15

• 60