Question

when there are seven rows in class mark we take the fifth one as assume mean then when there are 6 rows in class mark which ro will be taken as assume

Answer 1

Permutation of n different objects The number of permutations of n objects

taken all at a time, denoted by the symbol nPn

, is given by

P

n

n = n , ... (1)

where n = n(n – 1) (n – 2) ... 3.2.1, read as factorial n, or n factorial.

The number of permutations of n objects taken r at a time, where 0 < r ≤ n,

denoted by nPr

, is given by

nPr

=

n

n r −

We assume that 0 1