Hi,
I have doubts regarding the following questions.Please suggest how to go about it.
1)Using the digits 2,3,4,5,6 find the following:-
a)Sum of all 5 digit nos. that can be formed such that no 2 digits are the same.
b)Sum of all 4 digit nos. that can be formed such that no 2 digits are the same.
c)Sum of all 4 digit nos. that can be formed such that digits can be repeated.
The book I am referring to has used the below formula to solve the above question:_
(2+3+4+5+6)= sum of digits
(11111)= As many 1's as there are digits in the number.
(4!) =no. of times any digit appears in any place.
But I don't understand the exact usage of the formula.
2)A group of 11 people went to a party.There were 5 girls and 6 boys who were seated on a rectangular table with 6 chairs on either side of the longer edge.
a) What is the total no. of ways the group could be seated(Sides are indistinguishable)?
b)What is the no. of ways they can be seated so that all the 5 girls were sitting on the same side?
Thanks in advance.