Open QA 1-1

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course MTH 151

Time of submission: 11:40 PM, 5 Feb 2012

If your solution to stated problem does not match the given solution, you should self-critique per instructions athttp://vhcc2.vhcc.edu/dsmith/geninfo/labrynth_created_fall_05/levl1_22/levl2_81/file3_259.htm

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Your solution, attempt at solution. If you are unable to attempt a solution, give a phrase-by-phrase interpretation of the problem along with a statement of what you do or do not understand about it. This response should be given, based on the work you did in completing the assignment, before you look at the given solution.

006. Sequences and Patterns

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Question: `q001. Note that there are 6 questions in this assignment.

Find the likely next element of the sequence 1, 2, 4, 7, 11, ... .

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Your solution:

- I would first examine the problem and attempt to find a pattern in the manner of which addition is used. For example, I would see that 1+1 = 2, 2+2 = 4, 4 + 3 = 7, 7 + 4 = 11, and so on. Continuing this pattern of increasing the number added to the previous, we find that the next element in this list would be 11 + 5 = 16.

confidence rating #$&*: 3

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Given Solution:

The difference between 1 and 2 is 1; between 2 and 4 is 2; between 4 and 7 is 3; between 7 and 11 is 4. So we expect that the next difference will be 5, which will make the next element 11 + 5 = 16.

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Self-critique (if necessary):

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Self-critique Rating:

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Question: `q002. Find the likely next two elements of the sequence 1, 2, 4, 8, 15, 26, ... .

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Your solution:

- Using the same logic from the previous problem, would gathers that there’s an increasing pattern. 1, 2, 4, 7, 11. This pattern increases by one each number (in other words, 1 + 1 is 2, 2 + 2 is 4, 4 + 3 is 7, and so on) so one can continue the pattern to find the solution. 1, 2, 4, 7, 11, 16, 22. Comparing this to the sequence given in the problem, we discover that we get 1, 2, 4, 8, 15, 26, 42, 64.

confidence rating #$&*: 3

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Given Solution:

The difference between 1 and 2 is 1; the difference between 2 and 4 is 2, the difference between 4 and 8 is 4; the difference between 8 and 15 is 7; the difference between 15 and 26 is 11.

The differences form the sequence 1, 2, 4, 7, 11, ... . As seen in the preceding problem the differences of this sequence are 1, 2, 3, 4, ... .

We would expect the next two differences of this last sequence to be 5 and 6, which would extend the sequence 1, 2, 4, 7, 11, ... to 1, 2, 4, 7, 11, 16, 22, ... .

If this is the continuation of the sequence of differences for the original sequence 1, 2, 4, 8, 15, 26, ... then the next two differences of this sequence would be 16 , giving us 26 + 16 = 42 as the next element, and 22, giving us 42 + 22 = 64 as the next element. So the original sequence would continue as

1, 2, 4, 8, 15, 26, 42, 68, ... .

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Self-critique (if necessary): With respect and humility, wouldn’t the given solution be written as 1, 2, 4, 8, 15, 26, 42, *64* and not 68? Perhaps I missed something, but I thought that one should alert you to a possible discrepancy.

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Self-critique Rating:

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Right. The given solution reasoned out that the next element would be 42 + 22 = 64; the 68 in the last line appears to be a typo. Thanks for pointing it out.

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Question: `q003. What would be the likely next element in the sequence 1, 2, 4, 8, ... . It is understood that while this sequence starts off the same as that in the preceding exercise, it is not the same. The next element is not 15, and the pattern of the sequence is different than the pattern of the preceding.

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

- 16. One sees that there’s a pattern that resembles multiplication, each number is multiplied by two. 8 x 2 is 16, therefore, we end up with 1, 2, 4, 8, 16.

confidence rating #$&*: 3

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Given Solution:

One obvious pattern for this sequence is that each number is doubled to get the next. If this pattern continues then the sequence would continue by doubling 8 to get 16. The sequence would therefore be 1, 2, 4, 8, 16, ... .

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Self-critique (if necessary):

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Self-critique Rating:

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Question: `q004. There are two important types of patterns for sequences, one being the pattern defined by the differences between the numbers of the sequence, the other being the pattern defined by the ratios of the numbers of the sequence. In the preceding sequence 1, 2, 4, 8, 16, ..., the ratios were 2/1 = 2; 4/2 = 2; 8/4 = 2; 16/8 = 2. The sequence of ratios for 1, 2, 4, 8, 16, ..., is thus 2, 2, 2, 2, a constant sequence. Find the sequence of ratios for the sequence 32, 48, 72, 108, ... , and use your result to estimate the next number and sequence.

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Your solution:

- 162. Ratio found to be 3/2 or 1.5 so to find the next number 108 was multiplied by 1.5 to get 162.

confidence rating #$&*: 2

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Given Solution:

The ratios are 48/32 = 1.5; 72 / 48 = 1.5; 108/72 = 1.5, so the sequence of ratios is 1.5, 1.5, 1.5, 1.5, ... . The next number the sequence should probably therefore be 108 * 1.5 = 162.

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Self-critique (if necessary):

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Self-critique Rating:

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Question: `q005. Find the sequence of ratios for the sequence 1, 2, 3, 5, 8, 13, 21... , and estimate the next element of the sequence.

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Your solution:

- Found the ratio sequence - 2, 1/5, 1.666, 1.6, 1.625, 1.615

Estimation wasn’t understood.

confidence rating #$&*: 1

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Given Solution:

The ratios are 2/1 = 2; 3/2 = 1.5; 5/3 = 1.66...; 8/5 = 1.60; 13/8 = 1.625; 21/13 = 1.615. The sequence of ratios is 2, 1.5, 1.66..., 1.625, 1.615, ... .

We see that each number in the sequence lies between the two numbers that precede it --

1.66... lies between 2 and 1.5;

1.60 lies between 1.5 and 1.66...;

1.625 lies between

1.66... and 1.60;

1.615 lies between 1.60 and 1.625.

We also see that the numbers in the sequence alternate between being greater than the preceding number and less than the preceding number, so that the intervals between the numbers get smaller and smaller.

So we expect that the next number in the sequence of ratios will be between 1.615 and 1.625, and if we pay careful attention to the pattern we expect the next number to be closer to 1.615 than to 1.625.

We might therefore estimate that the next ratio would be about 1.618. We would therefore get

1.618 * 21 = 33.98

for the next number in the original sequence. However, since the numbers in the sequence are all whole numbers, we round our estimate up to 34.

Our conjecture is that the sequence continues with 1, 2, 3, 5, 8, 13, 21, 34, ... .

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Self-critique (if necessary): Wasn’t sure how to continue with this type of sequence; I understood the actual 2/1, 3/2, etc…And how it relates, but I couldn’t determine what to do after without consulting the Given Solution.

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Self-critique Rating:

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Question: `q006. Without using ratios, can you find a pattern to the sequence 1, 1, 2, 3, 5, 8, 13, 21, 34, ..., and continue the sequence for three more numbers?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

- One would find, after working through the usual patterns, that a possibility wouldn’t be discovered until one looks to find that, in a similar fashion to the previous problem, the first two elements would directly affect the next in the sequence. Thus, we find that it becomes 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144

confidence rating #$&*:

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Given Solution:

The pattern is that each element from the third on is the sum of the two elements that precede it. That is,

1+1=2,

2+1=3;

3+2=5;

5+3=8;

8+5=13;

13+8=21;

21+13=34;

. The next three elements would therefore e

34+21=55;

55+34=89;

89+55=144.

. The sequence is seen to be 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ... .

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Self-critique (if necessary):

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Self-critique rating:

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Question: `q006. Without using ratios, can you find a pattern to the sequence 1, 1, 2, 3, 5, 8, 13, 21, 34, ..., and continue the sequence for three more numbers?

YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY

Your solution:

- One would find, after working through the usual patterns, that a possibility wouldn’t be discovered until one looks to find that, in a similar fashion to the previous problem, the first two elements would directly affect the next in the sequence. Thus, we find that it becomes 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144

confidence rating #$&*:

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Given Solution:

The pattern is that each element from the third on is the sum of the two elements that precede it. That is,

1+1=2,

2+1=3;

3+2=5;

5+3=8;

8+5=13;

13+8=21;

21+13=34;

. The next three elements would therefore e

34+21=55;

55+34=89;

89+55=144.

. The sequence is seen to be 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, ... .

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Self-critique (if necessary):

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Self-critique rating:

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&#This looks good. See my notes. Let me know if you have any questions. &#