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Double Proportion Problem
Posted by slim on June 17, 2020 at 11:07 amI’m working on this double proportion problem I found in American Surveyor magazine and I’m getting the correct easting but my northing is the incorrect. I’m not in a PLSS state so I rarely work with sections, but I am preparing for both the PS and PLS exams so any clarification on what I’m doing wrong will be very helpful. I’m getting C but the correct answer is A. Thanks.
Here is a link to the actual page if the image doesn’t come through clearly: (Question 4)
http://archive.amerisurv.com/PDF/TheAmericanSurveyor-TestYourselfWithAnswers-March-April2004.pdf
aliquot replied 3 years, 10 months ago 13 Members · 56 Replies- 56 Replies
Need a better picture. This one is too blurry to read the cornnuts. I tried everything in my photo programs to make a decent picture, but it would not clear up so that it is readable.
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Something is missing from that question. Do you know what it is?
Looking at the other questions there are other problems too. I can assure you NCEES does a better job writing questions than this.
This is not a Double Proportion corner since it is a ?¬ corner and not a section corner and is a Single Proportion for reestablishment. I come up with C as the cornnuts for the ?¬ corner to Sections 9 and 16.
wouldn’t you dp the section corner then sp the quarter section corner?
Assuming the north-south section line is cardinal North and 80 chains plus 40 chains (GLO record) AND the east-west section line is cardinal east with given distances in chains (GLO record) I get answer A.
coordinates at the corner common to 8/9/16/17 are N19,926.667; E7,603.609.
@dave-karoly I got to thinking about this and I should have proportioned in the section corner first and then single proportioned in the ?¬ corner. Must be a sign Old Age is creeping up on me.
@dave-karoly You didn’t complete the problem. It asks for the ?¬ corner to Sectipns 9 & 16. I get the same cornuts as you for the section corner. I’ll redo my single proportion for the ?¬ corner tomorrow.
@charles-l-dowdell Thanks, I wasn’t doing that but using this method gets me the correct answer!
Quick breakdown:
Northing of section corner 8,9,16 & 17 is 19926.67 so:
19926.67+(40.05/80.10)(19800.00-19926.67)=19,863.335
I was right there the entire time, I was caught up on using only the given original monuments.
Hopefully like one of the others suggested, if a problem like this is to come up for me on my exam its worded a little different and asking for just the section corner.
I computed the answer in red. I screwed up the first time and put all the corners on the east-west line in-line with the existing corners. But that line will deflect at the double-proportioned section corner. I’m guessing that’s the the original poster in this thread got the easting correct, but the northing wrong. Two steps – 2P the section corner, then 1P the quarter corner on that new line.
my post last night is confusing, it was late.
i did calculate my way to answer A but it’s confusing how I posted the coordinates for the section corner at the end like that.
My calculation:
No bearings, no chains, no notes, no answer. I suppose you can “assume” all the elements that go into a calculation, but even for the N1/4 of Section 16 it’s critical that you know at least if the north line of 16 is an even or odd chain length. That will effect the 1/4 location.
- Posted by: @mightymoe
No bearings, no chains, no notes, no answer. I suppose you can “assume” all the elements that go into a calculation, but even for the N1/4 of Section 16 it’s critical that you know at least if the north line of 16 is an even or odd chain length. That will effect the 1/4 location.
The record north lines of 17 and 16 are given in chains. I can’t read the coordinates for certain due to the fuzzy picture.
. Those questions were written by Dr. Elgin and that is exactly how the MO, AR and KS State Specific Exam is written. When we were all studying for the tests years ago we called it “Dick Trickery”.
When studying for these tests always slow down and read them all twice – devil is in the details, usually multiple steps to get to final. This process tests not only math but the fundamentals of correct process. If your math is FUBAR but process is correct Dr. Elgin would give you partial credit on exams.
The answer is A for the ?¬ corner to Sections 9 & 16. This question is both a Double Proportion & Single Proportion problem.
Attached is a plot I made showing the complete results after all the calc’s were done. For some reason the scan put a break in the section line from the corner to Sections 16-17-20-21 to the corner to Sections 8-9-16-17, but it should be a straight line.
you can click on the link in the OP and get a clear page of it.
Guys this question is screwed up, you are all assuming the original record is cardinal. The original berings are not provided, so it can’t be solved.
The assumption that the north south bearing is cardinal is an especially bad assumption. Even if we assumed this township was perfect, this section line would not be cardinal.
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