Question
a library shelf contains 7 books. in how many ways can they be arranged if there are no restrictions?
b. the mathamatics text book must be first.
c.the 3 math text boooks must be together
b. the mathamatics text book must be first.
c.the 3 math text boooks must be together
Answers
Reiny
a) 7!
b) 1 x 6!
c) treat the 3 math books as one item, pretend they are bundled together, so there are 5 items to arrange.
for 5! ways.
b) 1 x 6!
c) treat the 3 math books as one item, pretend they are bundled together, so there are 5 items to arrange.
for 5! ways.
Craig
c)3! x 6!
The three must remain together but can be in any permutation with the rest. It would be 5! ways if the three books had to be in a certain position.
The three must remain together but can be in any permutation with the rest. It would be 5! ways if the three books had to be in a certain position.