PrepTest 119, Section 3, Question 6
Heavy salting of Albritten's roads to melt winter(91 more words not shown)
Which one of the following,(7 more words not shown)
- AEven water that(14 more words not shown)
- BThe concentration of(17 more words not shown)
- CSalting icy roads(10 more words not shown)
- DAlbritten's groundwater contained(11 more words not shown)
- ESalting of Albritten's(10 more words not shown)
Reading the argument
Is the road salt responsible for all that salt in the groundwater?
Albritten salts its roads heavily and has saltier groundwater than a nearby area that uses little road salt. That makes the proposed connection plausible. But two places can differ in other ways too. Perhaps some of Albritten's salt comes from another source. The comparison doesn't tell us how salty Albritten's own water was before heavy road salting began.
The author goes further and predicts that continuing at the present rate will make the groundwater taste unacceptably salty within a few decades. That needs more than a possible connection: it needs enough additional salt, quickly enough, to reach 250 milligrams per liter from the current 100.
What we’re looking for
For a weakener, my first thought is a reason to question whether road salting explains the higher salt level. Keep the actual forecast in view as well. We're assessing what would happen if the present salting rate continued, not whether the town might decide to change its policy.
Working the answers
- A
Safe to drink isn't the same as pleasant to drink. Water could be harmless and still taste unpleasantly salty. The conclusion concerns taste, so a much higher safety threshold doesn't challenge the stated taste threshold or the prediction of reaching it.
- B
Reaching 400 milligrams per liter within a few decades would put the water above the stated 250-milligram threshold. That fits the forecast of unacceptably salty water rather than weakening it.
- C
Preventing road accidents could be a reason to salt the roads despite an environmental drawback. But the author isn't deciding whether the benefit justifies the cost. The conclusion predicts a change in groundwater taste, and the usefulness of salting roads doesn't make that prediction less likely.
- DCorrect
Albritten started at roughly 90 milligrams per liter and is now at 100. That is an increase of only 10 over 20 years, not the 90-point increase we might infer by treating the neighboring area's 10 as Albritten's old level.
This challenges the timing even if road salt did cause the increase. At that same rate of increase, adding the remaining 150 milligrams would take about 300 years. That calculation isn't a guarantee about future groundwater conditions. It shows why the actual starting point gives us much less reason to predict an increase to 250 within just a few decades.
- E
The conclusion is conditional on continuing at the present rate. Saying that salting will probably decrease doesn't show what would happen if it continued unchanged. It describes a different future from the one the author is predicting the consequences of.
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