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LS Exam Problem
Posted by jeff-wright on August 7, 2011 at 2:51 amI was looking through some old test questions for the California Exam and found this one with the accepted answer:
The problem is simple, just convert a set of project coordinates from meters to feet.
“You are asked to convert a project coordinate from meters to feet.
Given X = 1,925,786.624m and Y = 542,065.352m, what values (to the nearest hundredth of a foot) should be reported to the client?
CORRECT RESPONSE AND ANSWER CRITERIA
Answer: 2 points
Only the numerical answers in the boxes below are required, with units.
X or E = (X x 39.37)/12
X or E = (1,925,786.624 x 39.37)/12
X or E = 6,318,184.95ft ± 0.02ftY or N = (Y x 39.37)/12
Y or N = (542,065.352 x 39.37)/12
Y or N = 1,778,426.08ft ± 0.02ft“My question is, why are the answers listed as +/-0.02ft? Does that mean that they will accept answers anywhere within that range or should the correct response include “+/-0.02ft”?
Only “23% of the candidates got the correct answer for this question.” That’s a little scary.
Thanks,
JeffThanks,
JeffDane Ince replied 12 years, 8 months ago 12 Members · 14 Replies- 14 Replies
The correct answer should include +/-0.01′.
I would say a good portion of the wrong answers assumed the conversion using International not US Survey feet.
Pail in US Survey foot PA
> I was looking through some old test questions for the California Exam and found this one with the accepted answer:
>
> 2004 CA Exam Question
>
> The problem is simple, just convert a set of project coordinates from meters to feet.
>
> “You are asked to convert a project coordinate from meters to feet.
> Given X = 1,925,786.624m and Y = 542,065.352m, what values (to the nearest hundredth of a foot) should be reported to the client?
> CORRECT RESPONSE AND ANSWER CRITERIA
> Answer: 2 points
> Only the numerical answers in the boxes below are required, with units.
> X or E = (X x 39.37)/12
> X or E = (1,925,786.624 x 39.37)/12
> X or E = 6,318,184.95ft ± 0.02ftY or N = (Y x 39.37)/12
> Y or N = (542,065.352 x 39.37)/12
> Y or N = 1,778,426.08ft ± 0.02ft“
>
> My question is, why are the answers listed as +/-0.02ft? Does that mean that they will accept answers anywhere within that range or should the correct response include “+/-0.02ft”?
>
> Only “23% of the candidates got the correct answer for this question.” That’s a little scary.
>
> Thanks,
> Jeff
I only see the two answers, that have the UNITSi think the +- is ther to try and through off the canidate.
The 0.02′ is to show you the range of acceptable responses.
Cited problem from California LS Exam
Question 7.
You are asked to convert a project coordinate from meters to feet.
Given X = 1,925,786.624m and Y = 542,065.352m, what values (to the nearest hundredth of a foot) should be reported to the client?Response:
Unless specified otherwise, feet are assumed to be Feet International. If the conversion was to be to US Survey Feet, it should be stated (Refer to NIST Special Publication 811).The conversion from meters to Feet International is:
1 foot = 0.3048 meters
The conversions, in terms of the question parameters, nearest hundredth of a foot, are:
X: 1 925 786.624 / 0.3048 = 6 318 197.59 ft
Y: 542 065.352 / 0.3048 = 1 778 429.63 ftThere is nothing in the problem statement to justify the values should be qualified by the tolerance ± 0.02 ft.
The “boxed” answers in the cited problem example are incorrect.
X or E = 6,318,184.95ft ± 0.02ft
Y or N = 1,778,426.08ft ± 0.02ftUsing US Survey Feet:
1 US Survey Foot = (1200/3937) m, the conversions are:
X: 1 925 786.624 / (1 200 / 3 937) = 6 318 184.95 ft
Y: 542 065.352 / (1 200 / 3 937) = 1 778 426.08 ftThe discussion presented may explain the statement “Only ‘23% of the candidates got the correct answer for this question.'” In actuality, as exemplified above, it may be that 77% got the correct answer but, 23% got the INCORRECT accepted answer. THAT IS SCARY!
Probably the reason for the ….
+/- .02 is to recognize the .04 that always shows up. Seriously, probably several people worked the problem with different calculators and different techniques and were getting round offs they couldn’t account for. The best way to work this problem is to do the division first and then the multiplication so as to keep numbers smaller. Get too big a number and you might have some round off / truncation errors in the calculator.
California use US Survey Foot, not International Foot.
Probably the reason for the ….
I agree with David Ingram. I don’t think you put the +/-0.02 as part of your answer. You just might have a calculator that can’t carry that big of digit out far enough to get the precise answer.
“the Board is releasing one question from one problem, along with the correct response and the answer criteria, from the 2004 California State Specific Professional Land Surveying examination. 23% of the candidates got the correct answer for this question. Please be aware that this question is only a portion of an entire problem from the examination.”…
“NOTICE: The release of this question does not change the secured nature of the entire April 2004 California State Specific Professional Land Surveying examination; all other questions and problems from the April 2004 California State Specific Professional Land Surveying examination remain secured.”
Sounds to me like they (the board) threw this quest out (released it) for that particular exam after scoring revealed such a skewed number answered incorrectly…? hard to tell
The Board released this because of the low percentage of examinees that obtained a correct response. Correct answers were not required to include the +-0.02′ tolerance. That was shown on the released portion to show what was considered an acceptable range.
The acceptable range was allowed in case someone wrote down intermediate values, then re-entered them in a calculator vs. storing and retrieving an internal value that carried more digits. The object was to demonstrate that an examinee knew how to apply the appropriate conversion factor for use in CA.
>released this because of the low percentage of examinees that obtained a correct response
>The object was to demonstrate that an examinee knew how to apply the appropriate conversion factor for use in CA.
A low percentage of examinees getting a correct response is certainly a tip-off that the question should be reviewed to see if it is clear and unambiguous.
But this one sounds like a legitimate unambiguous question that should be kept to separate the knowledgeable from the ill-prepared. You don’t want a PLS doing work with the wrong factor for your state plane system.
.> >released this because of the low percentage of examinees that obtained a correct response
>
> >The object was to demonstrate that an examinee knew how to apply the appropriate conversion factor for use in CA.
>
> A low percentage of examinees getting a correct response is certainly a tip-off that the question should be reviewed to see if it is clear and unambiguous.
>
> But this one sounds like a legitimate unambiguous question that should be kept to separate the knowledgeable from the ill-prepared. You don’t want a PLS doing work with the wrong factor for your state plane system.This is true. MI has (had) two coordinate systems, one which used the Clarke Ellipsoid and US Survey feet, the other the NAD 83 ellipsoid w/ meters (or international feet)- Use of the older system was prohibited after 1989. I’m surprised CA uses only US Survey feet, but nonetheless, seems PS candidates would know their State’s coordinate system. If this was a non-multiple ‘guess’ exam, could partially explain why the bulk of takers failed to use the correct conversion.
> A low percentage of examinees getting a correct response is certainly a tip-off that the question should be reviewed to see if it is clear and unambiguous.
>
> But this one sounds like a legitimate unambiguous question that should be kept to separate the knowledgeable from the ill-prepared. You don’t want a PLS doing work with the wrong factor for your state plane system.That’s one possible interpretation, Bill, and the one I had presumed before my first session as a grader on the CA exam.
Another possible interpretation is that the candidate pool was poorly educated (not implying need for college here – just making a general statement) and ill-prepared. Consider that CA has among the lowest set of requirements set by the individual states to be admitted to take the exam. Is it possible that has something to do with the exam’s reputation for being so tough?
Just to make that point a bit clearer, if you gave an algebra exam, offering a $100 gift certificate to a video game store and allowed anyone who has passed the 3rd grade to take the exam, you will have a much lower pass rate than if you limited it to those who have passed the 9th grade. With an incentive that appeals to 4th graders as much as to 10th graders, you will also get a much larger pool of takers.
Upon polling all those who had taken the exam, if open to anyone above the 3rd grade, the general consensus as to how tough the exam is would be far different that if you polled only those above the 9th grade. When you let the 4th graders take the exam, you also get a lot more who whine about how unfair it is when they don’t pass.
If you were to compare CA exam pass stats to other western states, you’d find some interesting numbers. Most of the other states have 10 to 50 (PLS) test takers per year. CA generally has 400 to 500. If you look at pass rates on the national exams (NCEES: LSIT/FLS, PLSS, Principles and Practices), you generally see that most of the other states have pretty consistent and comparable pass rates while CA consistently lags the other states by about 10 percentage points across the board.
If the PLS exam instructions, both printed and reiterated in oral instructions by the proctor state that units must be included with numerical answers, the answer is worth 3 points (hypothetically), and an examinee loses 1 point for neglecting to state units, is that fair?
IMO, it is. Part of the question measures the ability to follow instructions and provide what is asked for.
Over the past 5 years or so, the CA pass rates have been significantly higher than in previous years (mid 20s to mid 30s as compared to low to mid teens). Some of that success is due to increased educational and review opportunities provided through CLSA chapters, junior colleges, and private organizations. Part may be due to the Board having released some earlier exams and examinees realizing they are available and so knowing better what to expect.
MY guess is
Since the 2004 release goes into detail about UNITS, I would guess that many people failed to properly indicates the correct units, even though they did the conversion correctly. Some used the conversion or their calculators(which is wrong for US survey feet) and some did not attempt the problem. Add all these up ad this accounts for the poor performance on an easy question.
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