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Manager
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The Earth s rivers constantly carry dissolved salts into its [#permalink]
14 Jul 2005, 16:19
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The Earth’s rivers constantly carry dissolved salts into its oceans. Clearly, therefore, by taking the resulting increase in salt levels in the oceans over the past hundred years and then determining how many centuries of such increases it would have taken the oceans to reach current salt levels from a hypothetical initial salt-free state, the maximum age of the Earth’s oceans can be accurately estimated.
Which of the following is an assumption on which the argument depends?
1)The quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years.
2)At any given time, all the Earth’s rivers have about the same salt levels.
3)There are salts that leach into the Earth’s oceans directly from the ocean floor.
4)There is no method superior to that based on salt levels for estimating the maximum age of the Earth’s oceans.
5)None of the salts carried into the Earth’s oceans by rivers are used up by biological activity in the oceans
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Director
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B and E are the best options and it could be B.....
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SVP
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Re: I like this CR... [#permalink]
14 Jul 2005, 19:46
B. if the level of salt deposits every year is constatnt, then only the age of the ocen can be determined. so B is correct.
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Senior Manager
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E. the assumption assumes that all salts accumulated are always present and are never consumed....
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Intern
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In my opinion A
If we negate this assumption then our conclusion to calculate the age of the oceans will not hold.
Vik
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Manager
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There've been a lot of fight over A and E...
A is preferrable though...
Reason??
Cos E might be happening for years [ decades before] so it balances out
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Senior Manager
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This has been discussed earlier.
Consensus was A.
HMTG.
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Director
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E can be easily taken OUT
E says, biological reactions chew up a small portion of the salt. If that is the case, it has been probably happening every year with no exception.
B says about rivers. We dont care about rivers. We care about the collected water in the ocean. If the salt content changes in rivers, there would be cases when one river has more salt and other has less.
C is out of scope.
D is wrong too.
A is best. If the oceans had unusual fluctulations in last century, garbage in - garbage out. All the calculations will be wrong.
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Intern
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I believe A is the right answer?
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Manager
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Yup..Jerry, OA is A
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