Question

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.

Answer 1

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

Step-by-step explanation:

Option E is the best answer. In the text is says that "the engineering 'rules of thumb' by which thousands of bridges had been built around the world went down with Quebec Bridge." This shows that the "rules of thumb" that were used in the 18th century could completely assure the safety of bridges under construction. The passage then goes on to say that engineers relied on a more rigorous mathematical analysis. This lets us infer that the original analysis was insufficient. Option A is wrong because not all bridges were unsafe for public use. There are still bridges that are used by the public today that were built in the 18th century. Option B is simply false. Option C is incorrect because we don't actually know anything about the analytical methods of the time period. Option D is also wrong because we don't know if that is the only solution to the problem.

Answer 2

B - Coopers absences from the Quebec Bridge site resulted in the breaking off of the cantilever.

If Cooper had been onsite for the bridge construction, it would have saved time - allowing them to stop construction and the several dozen workers time to escape. It too valuable time to send the telegraph, to locate Cooper and have him read it as well as return the telegraph.