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gmatusa2010
- Master | Next Rank: 500 Posts
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- Joined: Sun Jul 25, 2010 5:22 am
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I noticed these types of problems occurred often, I wanted to come up with some properties, can someone confirm/disprove them?
Rules: All numbers in set are integers
1) For set of consecutive items, if number of item is odd => average is integer
1a) The reverse is not true, average is integer, number of item is odd, could be consecutive or not.
2) For set of evenly-spaced items, if number of item is odd=> average is integer (item 1 is a subset of 2)
2a) The reverse is not true.
3) For set of consecutive items, if number of item is even => average is NOT integer
3a) Reverse is not true
4) For set of evenly-spaced items, if number of item is even=> average could or could not be an integer
4a) For set of evenly-spaced items, if number of item is even=> average is an integer if the difference between the items are even.
4b) For set of evenly-spaced items, if number of item is even=> average is not an integer if the difference between the items are odd.
Rules: All numbers in set are integers
1) For set of consecutive items, if number of item is odd => average is integer
1a) The reverse is not true, average is integer, number of item is odd, could be consecutive or not.
2) For set of evenly-spaced items, if number of item is odd=> average is integer (item 1 is a subset of 2)
2a) The reverse is not true.
3) For set of consecutive items, if number of item is even => average is NOT integer
3a) Reverse is not true
4) For set of evenly-spaced items, if number of item is even=> average could or could not be an integer
4a) For set of evenly-spaced items, if number of item is even=> average is an integer if the difference between the items are even.
4b) For set of evenly-spaced items, if number of item is even=> average is not an integer if the difference between the items are odd.
