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Permutations Combinations 1-1



1$5! = $
A24
B120
C720
D140


2${}^6{C_2} = $
A15
B30
C12
D48


3If ${}^n{C_3} = 35$, then $n!=?$
A24
B120
C720
D5040


4If $r!=720$ then ${}^8{C_r} = $
A56
B48
C30
D28


5${}^8{P_2} = $
A56
B28
C40
D36


6${}^7{P_4} = $
A1/3
B1/4
C1/2
D2/3


7${}^n{P_r} = $
A$ \dfrac{{{}^n{C_r}}}{{r!}}$
B$ {}^n{C_r} \times r!$
C$ {}^n{C_r} \times n!$
D$ {}^n{C_r} \times 2n!$


8In how many ways can the letters of the word 'LOVER' be arranged?
A120
B24
C60
D30


9In how many ways can the letters of the word 'BEAUTY' be arranged so that the words always start with $A$?
A15
B20
C60
D120


10In how many ways can the letters of the word 'BEAUTY' be arranged so that the words always start with $A$ and ends with $B$?
A56
B48
C30
D24