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March 15, 2026, 06:25:05 pm
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Author Topic: Arrangements  (Read 819 times)  Share 

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VVVCCCEEE

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Arrangements
« on: July 12, 2018, 11:41:23 pm »
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Hey, could someone help me with 13 and 14 c. I don't get the solutions. Thanks
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Opengangs

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Re: Arrangements
« Reply #1 on: July 12, 2018, 11:54:34 pm »
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Hey, VVVCCCEEE.

With these types of questions, a good start would be to visualise what's happening.

If we are given a three digit number, for example, think about what can be placed in each space.

_ _ _

The first place doesn't have any restrictions, so it'd have 5 possibilities.

The second place ONLY has the restriction that it can't be the first number, so we take that away from our "possible outcomes". The sake works with the third space.

Thinking about specifically what each place's possible outcome will then allow you to determine the total number of arrangements.
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S_R_K

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Re: Arrangements
« Reply #2 on: July 13, 2018, 12:23:40 pm »
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For 13(c): You can also form four-digit and five-digit numbers, all of which are greater than 700. Then find the number of ways of writing a three-digit number that is greater than 700, so you'll need to consider how many possibilities there are for the first, second, third digit. Then consider how you'll need to combine your answers for three-digit, four-digit and five-digit numbers.

Q14(c) is similar.
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