The number of permutations of n different things taking r at a time when 3 particular things are to be included is
A. n − 3Pr − 3
B. n − 3Pr
C. nPr − 3
D. r ! n − 3Cr − 3
Answer:D
The number of permutations of n different things taking r at a time when 3 particular things are to be included is
A. n − 3Pr − 3 B. n − 3Pr C. nPr − 3 D. r ! n − 3Cr − 3