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# During the construction of the Quebec Bridge in 1907

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During the construction of the Quebec Bridge in 1907  [#permalink]

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10 Dec 2014, 01:34
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Difficulty:

45% (medium)

Question Stats:

68% (02:16) correct 32% (02:25) wrong based on 629 sessions

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During the construction of the Quebec Bridge in 1907, the bridge's designer, Theodore Cooper, received word that the suspended span being built out from the bridge's cantilever was deflecting downward by a fraction of an inch (2.54 centimeters). Before he could telegraph to freeze the project, the whole cantilever arm broke off and plunged, along with seven dozen workers, into the St. Lawrence River. It was the worst bridge construction disaster in history. As a direct result of the inquiry that followed, the engineering "rules of thumb" by which thousands of bridges had been built around the world went down with the Quebec Bridge. Twentieth-century bridge engineers would thereafter depend on far more rigorous applications of mathematical analysis.

Which one of the following statements can be properly inferred from the passage?

A. Bridges built before about 1907 were built without thorough mathematical analysis and, therefore, were unsafe for the public to use.

B. Cooper's absence from the Quebec Bridge construction site resulted in the breaking off of the cantilever.

C. Nineteenth-century bridge engineers relied on their rules of thumb because analytical methods were inadequate to solve their design problems.

D. Only a more rigorous application of mathematical analysis to the design of the Quebec Bridge could have prevented its collapse.

E. Prior to 1907 the mathematical analysis incorporated in engineering rules of thumb was insufficient to completely assure the safety of bridges under construction.

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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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10 Dec 2014, 13:33
What is the difference between A & E?
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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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10 Dec 2014, 20:42
IMO E
The argument says before Twentieth-century the engineering team followed "rules of thumb to build bridges.
Quebec Bridge in 1907 collasped even after following rules...therefore these rules were not sufficient/safe and engineers started depending on far more rigorous applications of mathematical analysis
Only E summarizes the given argument....
A says all the bridges were unsafe....this is too extreme. We dont know whether the thumbrules are not sutaible for all the bridges ..
B....we don't know this....passage doesnot mention that coopers absence led to the accident
C..We dont have any information of bridges built before 1907...so OFS
D..OFS....we dont know this....
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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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Updated on: 11 Dec 2014, 23:23
1
During the construction of the Quebec Bridge in 1907, the bridge's designer, Theodore Cooper, received word that the suspended span being built out from the bridge's cantilever was deflecting downward by a fraction of an inch (2.54 centimeters). Before he could telegraph to freeze the project, the whole cantilever arm broke off and plunged, along with seven dozen workers, into the St. Lawrence River. It was the worst bridge construction disaster in history. As a direct result of the inquiry that followed, the engineering "rules of thumb"by which thousands of bridges had been built around the world went down with the Quebec Bridge. Twentieth-century bridge engineers would thereafter depend on far more rigorous applications of mathematical analysis.

INFERENCE- 1. TILL 1907 OLD THUMB RULES APPLIED.
2. AFTER THAT FAR MORE RIGOROUS APPLICATIONS OF MATHS ANALYSIS.

Which one of the following statements can be properly inferred from the passage?

A. Bridges built before about 1907 were built without thorough mathematical analysis and, therefore, were unsafe for the public to use. THEY MAY HAVE BEEN RIGOROUS, thoroughly analysed...premise never contradicts that---though NOW IT IS FAR MORE RIGOROUS.... hence WRONG
B. Cooper's absence from the Quebec Bridge construction site resulted in the breaking off of the cantilever..... NO SUCH INFERENCE. WRONG.
C. Nineteenth-century bridge engineers relied on their rules of thumb because analytical methods were inadequate to solve their design problems.... WE DONT KNOW WHY SUCH RULES APPLIED..... WRONG
D. Only a more rigorous application of mathematical analysis to the design of the Quebec Bridge could have prevented its collapse... HOW CAN WE SAY THAT.... ANY PROBLEM CAN HAVE TWO OR MORE SOLUTIONS .... JUST THAT ONE BEING DISCUSSED HERE....WRONG.
E. Prior to 1907 the mathematical analysis incorporated in engineering rules of thumb was insufficient to completely assure the safety of bridges under construction..... THATS BEEN PHYSICALLY PROVEN.......SEE INFERENCE 1 ABOVE.... TILL 1907 OLD THUMB RULES APPLIED. AND THE BRIDGE BROKE....
HENCE CORRECT.......

Originally posted by semwal on 11 Dec 2014, 02:24.
Last edited by semwal on 11 Dec 2014, 23:23, edited 1 time in total.
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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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11 Dec 2014, 06:07
Statement A is false. We can't infer from the text that " Bridges built before about 1907 were built without thorough mathematical analysis and, therefore, were unsafe for the public to use". Statement E can be infered
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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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12 Dec 2014, 06:27
LSAT question. Avoid such sources in my opinion for practice.

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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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02 Sep 2016, 23:47
D. Only a more rigorous application of mathematical analysis to the design of the Quebec Bridge could have prevented its collapse.
RIGHT, it clearly says only the new rule or new analysis could have prevented the collapse

E. Prior to 1907 the mathematical analysis incorporated in engineering rules of thumb was insufficient to completely assure the safety of bridges under construction.
WRONG, because it says only new analysis will help that are under construction and that to it says Prior to 1907 the existing mathematical analysis as thumb rule is unsafe for buildings which are under construction. If so many buildings would have collapsed prior to 1907.

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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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03 Sep 2016, 08:01
ravikrishna1979 wrote:
D. Only a more rigorous application of mathematical analysis to the design of the Quebec Bridge could have prevented its collapse.
RIGHT, it clearly says only the new rule or new analysis could have prevented the collapse

E. Prior to 1907 the mathematical analysis incorporated in engineering rules of thumb was insufficient to completely assure the safety of bridges under construction.
WRONG, because it says only new analysis will help that are under construction and that to it says Prior to 1907 the existing mathematical analysis as thumb rule is unsafe for buildings which are under construction. If so many buildings would have collapsed prior to 1907.

The passage says that twentieth-century bridge engineers would thereafter depend on far more rigorous applications of mathematical analysis - but it has not been mentioned whether such analysis could prevent collapse. It is as well possible that even after the analysis, some bridges collapse. hence statement D cannot be inferred.

I am not sure what is you point about option E - you yourself concluded that "thumb rule is unsafe" - so you are actually supporting that option E is correct.
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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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28 Jan 2018, 10:43
talismaaniac wrote:
What is the difference between A & E?

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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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28 Jan 2018, 13:32
why not B - if cooper was present, he could have stopped the construction... any one can enlighten me on the same... thanks in advance
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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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17 Feb 2018, 04:14
vishwash wrote:
why not B - if cooper was present, he could have stopped the construction... any one can enlighten me on the same... thanks in advance

If B is correct can you explain these lines of the passage.

As a direct result of the inquiry that followed, the engineering "rules of thumb" by which thousands of bridges had been built around the world went down with the Quebec Bridge.

The incident was more of a result of the use of "rule of thumb" rather absence of this guy. moreover what if he is present and could not have done those calculation.

IMO E
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Re: During the construction of the Quebec Bridge in 1907  [#permalink]

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29 Dec 2018, 23:19

The question requires the examinee to identify the response that can be properly inferred from the passage. The passage indicates that the Quebec Bridge disaster in 1907 and the inquiry that followed caused the engineering “rules of thumb” used in construction of thousands of bridges to be abandoned. Since the Quebec Bridge disaster in 1907 prompted this abandonment, it can be inferred that these were the rules of thumb under which the Quebec Bridge was being built when it collapsed and that these were the rules of thumb used in bridge building before 1907. Further, since the Quebec Bridge collapsed while under construction and the rules of thumb being used were abandoned as a result, it can be inferred that the rules of thumb used in building the Quebec Bridge and bridges prior to 1907 were insufficient to completely assure the safety of bridges under construction. Finally, since the alternative to the old engineering rules of thumb that was adopted was to “depend on far more rigorous applications of mathematical analysis,” it can be inferred that it was the mathematical analysis incorporated in the engineering rules of thumb used prior to 1907 that made them insufficient to completely assure the safety of bridges under construction. Thus, (E) is the credited response.

Response (A) is incorrect. (A) asserts that the lack of thorough mathematical analysis in the construction of bridges before about 1907 was sufficient to establish that those bridges were unsafe for the public to use. But, the rules of thumb used in bridge construction before 1907 were abandoned because they were not sufficient to establish that the bridges being constructed using them were safe when under construction. It does not follow that the lack of more rigorous or thorough mathematical analysis in the rules of thumb was sufficient to establish that the bridges built before about 1907 using them were unsafe even while under construction, let alone for the public. In fact, some, or even all, may have been quite safe. In addition, the passage gives evidence only about the safety of bridges built before 1907 while they were under construction. It is silent on whether bridges built before about 1907 were safe when open for use by the public.

Response (B) is incorrect in claiming that Cooper’s absence from the construction site caused the breaking off of the cantilever. The passage does not establish that, had Cooper been at the site, he could have successfully intervened to prevent the cantilever from breaking off. By freezing the project, he might have spared lives by stopping work, but there is nothing in the passage to indicate that he necessarily would have prevented the collapse.

Response (C) is incorrect; there is no evidence in the passage about why nineteenth-century engineers relied on their rules of thumb.

Response (D) is also incorrect. While the passage suggests that a more rigorous application of mathematical analysis would have prevented the collapse of the bridge, it offers no evidence that it is the only way the collapse could have been prevented. For example, it might have been prevented had corrective measures been taken in time.

OPTION: E
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Re: During the construction of the Quebec Bridge in 1907   [#permalink] 29 Dec 2018, 23:19
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