Question

1)How many „words‟ can be formed using letter of STUDENT using
each letter at most once:
i) If each letter must be used,
ii) If some or all the letters may be omitted.

Show whether ( p→q) ( q → p ) is a tautology or not using truth
table.

Answer 1

1.if each letter must be used
_ _ _ _ _ _ _
the 7 spaces can be filled in 7!/2!
2! is given because in the word 'STUDENT' "T" is used twice.