PrepTest 120, Section 3, Question 1
Although fiber-optic telephone cable is more expensive to(59 more words not shown)
The above statements, if true,(8 more words not shown)
- AThe material from(17 more words not shown)
- BThe increase in(20 more words not shown)
- CFiber-optic cable can(9 more words not shown)
- DSignals transmitted through(13 more words not shown)
- EThe cost associated(17 more words not shown)
Reading the argument
The cable costs more, but the network costs less. What else are we paying for?
A network includes more than the cable itself. Perhaps another part of the system is expensive, or perhaps one kind requires more supporting equipment. The passage supplies the particular explanation: copper signals need frequent amplification, while the light pulses in fiber-optic cable can travel farther before they need it. To explain the lower overall cost, that difference in amplification must save enough money to outweigh the extra cost of manufacturing the fiber-optic cable.
What we’re looking for
That's what I expect the most-supported answer to say. Don't just choose a fact that sounds plausible about these technologies. Connect the stated explanation to the cost difference it is supposed to explain.
Working the answers
- A
Manufacturing cost isn't necessarily the cost of the raw material. The material could be cheap while the manufacturing process is expensive. The passage says fiber-optic cable costs more to manufacture, but doesn't identify which part of manufacturing creates that extra expense. A isn't established, and it doesn't connect amplification with the overall savings.
- B
We aren't told that the number of transmissions is increasing or that copper networks are being strained by it. Needing frequent amplification over long distances doesn't itself establish either claim. The question is why one network costs more, not whether growing use is overwhelming it.
- C
Carrying more signals at once could be a useful advantage, but the passage doesn't give us that comparison. Its stated advantage concerns the distance signals can travel before amplification. Capacity and distance aren't interchangeable.
- D
We don't know the relative speeds. Traveling farther before needing amplification doesn't tell us whether a signal travels faster, slower, or at the same speed. D supplies a comparison the passage never makes.
- ECorrect
The extra amplification cost for copper outweighs the extra manufacturing cost for fiber-optic cable. That explains how fiber optics can cost more at the cable-manufacturing stage but less for the network overall.
If the amplification savings were too small to offset that higher initial cost, they wouldn't explain the overall cost advantage the passage attributes to them. E connects the reason given with the result we're asked to understand.
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