The number of permutations of n different things taken r at a time in which 4 particular things never occur is -

If the number of permutations of n different things taken 4 at a time in which one particular thing does not occur is equal to that in which it does occur,find n .

Find the number of permutations of n things taken r at a time in which two particular things : never occur.

Show that the numbers of permutations of n different things taken all at a time in which m particular things are never together is (n-m)!(n-m+1)! .

The number of combinations of n different things taken r at a time in which p particular things always occur is -

Find the number of permutations of n things, taken r at a time, in which 3 particular things : will never occur.

Find the number of permutations of n different things taken r at time so that m(ltr) particular things will never occur.

The number of combinations of n different of n different things taken r at a time in which p particular things never occur is -

The number of permutations of n different things taking r at a time when 3 particular things are to be included is a. \ ^(n-3)P_(r-3) b. \ ^(n-3)P_r c. \ ^n P_(r-3) d. \ r !^(n-3)C_(r-3)