Quebec Bridge

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Quebec Bridge

by durgesh79 » Fri Jun 27, 2008 4:50 am
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 [2.56 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 25
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.
Source: — Critical Reasoning |

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by niraj_a » Fri Jun 27, 2008 5:07 am
is it E buddy?

D is definitely out and A and C are tricky :)

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by newera » Fri Jun 27, 2008 7:47 am
I agree with niraj, I'm going for E.

A --we can't really claim that the bridges built in the past were without thorough mathematical analysis. thats a bold statement to make.
B --totally out
C --we don't know that
D --maybe, but again, the word "only" is too restrictive and raises a red flag
E --makes the most sense. moderate language.

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by raunekk » Fri Jun 27, 2008 11:26 am
definately E

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by chidcguy » Fri Jun 27, 2008 1:02 pm
A) Bridges built before about 1907 were built
without thorough mathematical analysis and,
therefore, were unsafe for the public to use.

Infers too much


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

TC's absence is not the reason.

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


we don't know whether analytical models of 19th century were inadequate or not.

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

Scope issue with only. Not good for inference Q's

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

makes a lot of sense because 20th century engineering rules added 25 more analysis rules

E is my pick, unless there is a big landmine :)
Please do not post answer along with the Question you post/ask

Let people discuss the Questions with out seeing answers.

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by durgesh79 » Fri Jun 27, 2008 1:31 pm
thanks Guys, OA is E

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by khanshainur » Wed May 11, 2016 12:44 am
I agree with you guys. I also think that the right answer is E