Liberal Arts Mathematics

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course Mth 152

Liberal Arts Mathematics

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Question: `q001. Consider the statement 'If that group of six-year-olds doesn't have adult supervision, they won't act in an orderly manner.' Under which of the following circumstances would everyone have to agree that the statement is false?

The group does have supervision and they do act in an orderly manner.

The group doesn't have supervision and they don't act in an orderly manner.

The group doesn't have supervision and they do act in an orderly manner.

The group does have supervision and they don't act in an orderly manner.

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Your solution:

The group doesn't have supervision and they do act in an orderly manner.

confidence rating #$&*:

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3

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Given Solution:

`aThe statement says that if the group doesn't have supervision, they will not act in an orderly manner. So if they don't have supervision and yet do act in an orderly manner the statement is contradicted.

If the group does have supervision, the statement cannot be contradicted because condition of the statement, that the group doesn't have supervision, does not hold. The statement has nothing to say about what happens if the group does have supervision.

Of course if the group doesn't have supervision and doesn't act in orderly manner this is completely consistent with the statement.

Therefore the only way to statement can be considered false is the group doesn't have supervision and does act in an overly manner.

Note that what we know, or think we know, about childrens' behavior has nothing at all to do with the logic of the situation. We could analyze the logic of a statement like 'If the Moon is made of green cheese then most six-year-olds prefer collard greens to chocolate ice cream'. Anything we know about the composition of the Moon or the tastes of children has nothing to do with the fact that the only way this statement could be shown false would be for the Moon to be made of green cheese and most six-year-olds to prefer the ice cream.

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Self-critique (if necessary):

I could have went into more detail about why I chose this answer

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Self-critique Rating:

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Question: `q002. List the different orders in which the letters a, b and c could be arranged (examples are 'acb' and 'cba'). Explain how you know that your list contains every possible order.

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Your solution:

The reason I know that my contains every possible combination is because I have used every letter as the first letter and consistently changed the last two letters to for every combination.

Abc

Bac

Cab

Acb

Bca

Cba

confidence rating #$&*:

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Given Solution:

`aThe only reliable way to get all possible orders is to have a system which we are sure the list every order without missing any.

Perhaps the simplest way to construct all possible orders is to list then alphabetically.

We start with abc. There is only one other order that starts with a, and it is obtained by switching the last two letters to get acb.

The next alphabetical order must start with b. The first possible listing starting with b must follow b with a, leaving c for last. The orders therefore bac. The only other order starting with b isbca.

The next order must start with c, which will be followed by a to give us cab. The next order is obtained by switching the last two letters to get cba.

This exhausts all possibilities for combinations of the three letters a, b and c. Our combinations are, in alphabetical order,

abc, acb, bac, bca, cab, cba.

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Self-critique (if necessary):

OK

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Self-critique Rating:

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Question: `q003. One collection consists of the letters a, c, d and f. Another collection consists of the letters a, b, d and g.

List the letters common to both collections.

List the letters which appear in at least one of the collections.

List the letters in the first half of the alphabet which do not appear in either of the collections.

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Your solution:

The letters common to both collections is a and d.

The letters that appear at least once in the collections is a, b, c, d, f, g

The letters that are in the first half of the alphabet and that do not appear in either of the collections are as follows. E, H, I, J, K, L, and M. The way I found this was by taking the number of letters in the alphabet which is 26 and dividing it in half to get 13 and then took the first 13 letters and marked out what was already in the list.

confidence rating #$&*:

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3

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Given Solution:

`aTo letters a and d each appear in both collections. No other letter does.

The letters a, c, d, and f appear in the first collection, so they all in at least one of the collections. In addition to letters b and g appear in the second collection. Therefore letters a, b, c, d, f and g all appear in at least one of the collections.

We consider the letters in the first half of the alphabet, in alphabetical order. a, b, c and d all appear in at least one of the collections, but the letter e does not. The letters f and g also appear in at least one of the collections, but none of the other letters of the alphabet do. The first half of the alphabet ends at m, so the list of letters in the first half of the alphabet which do not occur in at least one of the collections is e, h, i, j, k, l, m.

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Self-critique (if necessary):

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Self-critique Rating:

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Question: `q004. Give the next element in each of the following patterns and explain how you obtained each:

2, 3, 5, 8, 12, ...

3, 6, 12, 24, ...

1, 3, 4, 7, 11, 18, ...

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Your solution:

In the pattern 2, 3, 5, 8, and 12 can be seen by subtracting each number from the one after it. Which mean 3-2 = 1, 5-3 = 2, 8-5 = 3, and 12-8 = 4. So knowing that the difference is 1, 2, 3, 4,. The next difference will be 5, but in this case instead of subtracting we need to add 5 to 12 giving us the next number which is 17.

In the pattern 3, 6, 12, and 24 you can see that each number is divided into the one after it which gives us 6 / 3 = 2, 12 / 6 = 2, 24 / 12 = 2. This shows that we are simpily doubling each number to get the next one. So to get the next number we multiply 24 * 2 = 48 and to check the number we divide 48 by 2 which is 24 thus the next number in this sequence is 48

In the pattern of the sequence 1, 3, 4, 7, 11, and 18 we can see that every thired number is the answer to the first two before it added together. Knowing this the next number is 11 added to 18 which gives us 29. Thus the answer is 29.

confidence rating #$&*:

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3

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Given Solution:

`aThe pattern of the sequence 2, 3, 5, 8, 12, ... can be seen by subtracting each number from its successor. 3-2 = 1, 5-3 = 2, 8-5 = 3, 12-8 = 4. The sequence of differences is therefore 1, 2, 3, 4, ... . The next difference will be 5, indicating that the next number must be 12 + 5 = 17.

The pattern of the sequence 3, 6, 12, 24, ... can be discovered by dividing each number into its successor. We obtain 6/3 = 2, 12/6 = 2, 24/12 = 2. This shows us that we are doubling each number to get the next. It follows that the next number in the sequence will be the double of 24, or 48.

The pattern of the sequence 1, 3, 4, 7, 11, 18, ... is a little obvious. Starting with the third number in the sequence, each number is the sum of the two numbers proceeding. That is, 1 + 3 = 4, 3 + 4 = 7, 4 + 7 = 11, and 7 + 11 = 18. It follows that the next member should be 11 + 18 = 29.

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Self-critique (if necessary):

OK

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Self-critique Rating:

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Question: `q005. The number 18 can be 'broken down' into the product 9 * 2, which can then be broken down into the product 3 * 3 * 2, which cannot be broken down any further .Alternatively 18 could be broken down into 6 * 3, which can then be broken down into 2 * 3 * 3.

Show how the numbers 28 and 34 can be broken down until they can't be broken down any further.

Show that there at least two different ways to break down 28, but that when the breakdown is complete both ways end up giving you the same numbers.

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Your solution:

2 * 17 = 34 This cannot be broken down any farther.

2 * 14 = 28

2 * 7 = 14

2 * 2 * 7 = 28

confidence rating #$&*:

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3

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Given Solution:

`aA good system is to begin by attempting to divide the smallest possible number into the given number. In the case of 34 we see that the number can be divided by 2 give 34 = 2 * 17. It is clear that the factor 2 cannot be further broken down, and is easy to see that 17 cannot be further broken down. So the complete breakdown of 34 is 2 * 17.

To breakdown 28 we can again divide by 2 to get 28 = 2 * 14. The number 2 cannot be further broken down, but 14 can be divided by 2 to give 14 = 2 * 7, which cannot be further broken down. Thus we have 28 = 2 * 2 * 7.

The number 28 could also the broken down initially into 4 * 7. The 4 can be further broken down into 2 * 2, so again we get 28 = 2 * 2 * 7.

It turns out that the breakdown of a given number always ends up with exactly same numbers, no matter what the initial breakdown.

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Self-critique (if necessary):

I should have given a more verbalized explanation.

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Self-critique Rating:

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Question: `q006. Give the average of the numbers in the following list: 3, 4, 6, 6, 7, 7, 9. By how much does each number differ from the average?

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Your solution:

In order to do this problem we have to first find out what the average is by adding all of the number together then dividing by how many numbers there are which should be like so: 3+4+6+6+7+7+9 = 42

Then we take 42 and divide by how many numbers there are so 42/7 = 6

Now we need to find the difference between each number.

We can now see that 3 differs from 6 by 3, 4 differs from 6 by 2, 6 differs by 0, 6 differs by 0, 7 differs from 6 by 1, and 9 differs from 6 by 3. So the answers are as follows:

The average of 3, 4, 6, 6, 7, 7, 9 is 6

The difference is 3, 2, 0, 0, 1, 1, 3

confidence rating #$&*:

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3

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Given Solution:

`aTo average least 7 numbers we add them in divide by 7. We get a total of 3 + 4 + 6 + 6 + 7 + 7 + 9 = 42, which we then divide by 7 to get the average 42 / 7 = 6.

We see that 3 differs from the average of 6 by 3, 4 differs from the average of 6 by 2, 6 differs from the average of 6 by 0, 7 differs from the average of 6 by 1, and 9 differs from the average of 6 by 3.

A common error is to write the entire sequence of calculations on one line, as 3 + 4 + 6 + 6 + 7 + 7 + 9 = 42 / 7 = 6. This is a really terrible habit. The = sign indicates equality, and if one thing is equal to another, and this other today third thing, then the first thing must be equal to the third thing. This would mean that 3 + 4 + 6 + 6 + 7 + 7 + 9 would have to be equal to 6. This is clearly not the case. It is a serious error to use the = sign for anything but equality, and it should certainly not be used to indicate a sequence of calculations.

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Self-critique (if necessary):

OK

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Self-critique Rating:

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Question: `q007. Which of the following list of numbers is more spread out, 7, 8, 10, 10, 11, 13 or 894, 897, 902, 908, 910, 912? On what basis did you justify your answer?

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Your solution:

We can see that the first set of numbers range from 7 to 13 which show a difference of 6. In the second set they range from 894 to 912 which show a difference of 18.

So going by this we can see that the second set is spread out farther than the first.

The way that I derived at this conclusion was I looked at the spacing between the numbers. In the first set we are given differences of 1, 2, 0, 1, and 2. In the second set we are given 3, 5, 6, 2, and 2. We can tell just from looking at them that the variation in the second set is greater than the first.

confidence rating #$&*:

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Given Solution:

`aThe first set of numbers ranges from 7 to 13, a difference of only 6. The second set ranges from 894 to 912, a difference of 18. So it appears pretty clear that the second set has more variation the first.

We might also look at the spacing between numbers, which in the first set is 1, 2, 0, 1, 2 and in the second set is 3, 5, 6, 2, 2. The spacing in the second set is clearly greater than the spacing in the first.

There are other more sophisticated measures of the spread of a distribution of numbers, which you may encounter in your course.

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Self-critique (if necessary):

OK

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