ineedhelp33
New member
- Joined
- Nov 7, 2021
- Messages
- 2
Question:
On a shelf there are 4 different mathematics books and 8 different English books.
i) The books are to be arranged so that the mathematics books are together. In how many different ways can this be done?
Answer: 4!*9! = 8 709 120
I did not have any problem with the question and answer above, but the problem is the next one:
ii) What is the probability that none of the mathematics books are next to each other?
The working given for this question is ((8!)*(9P4))/(12!), but could anyone explain what is the logic behind this working?
On a shelf there are 4 different mathematics books and 8 different English books.
i) The books are to be arranged so that the mathematics books are together. In how many different ways can this be done?
Answer: 4!*9! = 8 709 120
I did not have any problem with the question and answer above, but the problem is the next one:
ii) What is the probability that none of the mathematics books are next to each other?
The working given for this question is ((8!)*(9P4))/(12!), but could anyone explain what is the logic behind this working?