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# Permutations and combinations watch

1. Can someone help me with this I cant understand it at all for example a questions like

How many numbers are there between 1245 and 5421 inclusice which contains each of the digits 1,2,4 and 5 once only? once of these numbers is chosen at random. dins the probability that it is

a) divisible by 5 b) greater than 3000

Everyone always states that stats is easy, at the moment stats > C4
2. since there is no repetition you can treat it as how many arrangements of 4 different items are possible...

it is the same as "how many ways can the letters of the word WINO be rearranged"
3. (Original post by the bear)
since there is no repetition you can treat it as how many arrangements of 4 different items are possible...

it is the same as "how many ways can the letters of the word WINO be rearranged"
4 factorial = 24

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4. (Original post by Dopey')
4 factorial = 24

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a) What do you know about numbers that are divisble by 5?

b) If it's greater than 3000, what are the number of choices for the 1st digit, then the second, third, fourth.
5. (Original post by ghostwalker)
a) What do you know about numbers that are divisble by 5?

b) If it's greater than 3000, what are the number of choices for the 1st digit, then the second, third, fourth.
I dont get what your trying to get across?
6. (Original post by Dopey')
I dont get what your trying to get across?
How to recognise which numbers satisfy the criteria.
7. (Original post by Dopey')
I dont get what your trying to get across?
comlpete the sentance. 'To be divisible by 5 a number must end in a ____'

If you can pin down one of the numbers, you then can work out how many combinations there are that satisfty this condition.....

for b) write down the lowest number you can which is higher than 3000. see what you notice about this condition.

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