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The Earth's rivers constantly carry dissolved salts into its oceans.

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Vaishali2004
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Re: The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   28 May 2022, 00:22
Choice A - Even if the rate of deposit of salt was not constant. We could still determine the age by assuming that a constant amount being depotited. That way, we would end up determining higher age of earth than in real. But the conclusion mentions "maximum age" So then wouldn't that still be okay?
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Re: The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   03 Jun 2022, 13:47
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Vaishali2004 wrote:
Choice A - Even if the rate of deposit of salt was not constant. We could still determine the age by assuming that a constant amount being depotited. That way, we would end up determining higher age of earth than in real. But the conclusion mentions "maximum age" So then wouldn't that still be okay?

Let's say that salt deposits HAVE been unusually high in the past century. If you used this data and mistakenly said that the same thing happened in previous centuries, you'd come up with a time estimate that is too short (as in, you'd think that the water got saltier in a shorter amount of time than it actually took). This would give you a (faulty) maximum age that is too recent. The actual maximum age would be older than your estimate.

So, you need to assume that quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years.

That's why (A) is an assumption on which the argument depends.

I hope that helps!
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Re: The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   31 Jul 2022, 06:31
bb wrote:
ttram wrote:
msday86 wrote:
I think the assumption is that the increase in salt level is constant throughout time. So, I think A is the answer. If the increase in level over the last 100 years in unusually high, then that invalidates the method.


I agree with you that A is right. However, what do you think about E?


After re-reading choice E several times (which I may not have done on the real GMAT), it seems to be irrelevant.
The argument says to take the difference between salt levels today and 100 years ago and then divide the total salt level by the difference. Choice E says that there may be some biological activities using up the salts, which is fine since these biological activities have been active longer than 100 years, so they are a constant. Every 100 years these biological activities consumed the same amount of salt. Surprisingly, choice E can be ruled out mathematically.
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The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   01 Aug 2022, 08:26
Hi avigutman - i selected (A). Quick question on (E).

When i read the argument, essentially the argument is saying : divide the the Green (Numerator) / Blue (Denominator) : You will get the age of the river.

Question on (E).

I did not select (E) because i thought (E) was baked into to the calculations of the green (numerator) to begin with.

Question - is (E) baked into the calculation of
(i) BOTH, the green and the blue
or
(ii) just the blue only
or
(iii) just the green only

As long as (E) is baked into one of these three options - we can eliminate (E) but i was curious
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Re: The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   01 Aug 2022, 19:23
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jabhatta2 wrote:
Hi avigutman - i selected (A). Quick question on (E).

When i read the argument, essentially the argument is saying : divide the the Green (Numerator) / Blue (Denominator) : You will get the age of the river.

Question on (E).

I did not select (E) because i thought (E) was baked into to the calculations of the green (numerator) to begin with.

Question - is (E) baked into the calculation of
(i) BOTH, the green and the blue
or
(ii) just the blue only
or
(iii) just the green only

As long as (E) is baked into one of these three options - we can eliminate (E) but i was curious

We can eliminate (E) because it's "baked in" to both the green and the blue. If it were only "baked in" to one of them, that would be a problem. We need the consistency in order for the calculation to be meaningful, jabhatta2.
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Re: The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   23 Nov 2022, 23:56
Zatarra wrote:
hibloom wrote:
Which of the following is an assumption on which the argument depends?

(A) The quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years.
(B) At any given time, all the Earth’s rivers have about the same salt levels.
(C) There are salts that leach into the Earth’s oceans directly from the ocean floor.
(D) There is no method superior to that based on salt levels for estimating the maximum age of the Earth’s oceans.
(E) None of the salts carried into the Earth’s oceans by rivers are used up by biological activity in the oceans.

i was a difficult choice between a and e.
I eliminated E with the foll. reasoning.
If at the beginning of the last century,the ocean contained x kgs of salt.
If in the last 100 years , 100 kgs of ice was dropped into the ocean by the rivers.
and suppose that in the past 100 yrs 5 kgs of salt was used up by the ocean because of its biological activity.
then 95 kgs was dropped in the last century.
So the level becomes x + 95
still we can find out the age of the ocean by taking 95 kgs as the average increase in 1 century.


But the option does not say in the last 100 years. It could be any of the set of 100 years and can change average salt in that particular slot of 100 years. How does it not affect the amount of the salt/100 years?
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The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   23 Sep 2023, 05:15
Pre-thinking - We assume that the deposition of salts has been pretty consistent. What if in the last 100 years, the deposition of slats was extremely high say because of industrial activity then the maximum age of Earth's oceans can't be accurately estimated.

(A) The quantities of dissolved salts deposited by rivers in the Earth’s oceans have not been unusually large during the past hundred years. - in line with our pre-thinking.

(B) At any given time, all the Earth’s rivers have about the same salt levels. - Doesn't matter. Irrelevant.

(C) There are salts that leach into the Earth’s oceans directly from the ocean floor. - At best, a weakener.

(D) There is no method superior to that based on salt levels for estimating the maximum age of the Earth’s oceans. - Not an assumption. The argument doesn't say that this is the superior method.

(E) None of the salts carried into the Earth’s oceans by rivers are used up by biological activity in the oceans. - At best, it's a strengthener. But it is not a necessary condition. Say we negate this - Some (at least 2 - say 2 kgs, for example) of salts ....are used for biological activity...does it even matter? No.
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Re: The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   04 Dec 2023, 09:22
I got that the answer is A but everyone is ignoring D. I wanted to understand why?
Lets say There is a superior method than the current method to determine the ocean's age, it means that the earlier method that has been used for the same is inaccurate because we have a better method to ensure accuracy?
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Re: The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink] New post   16 Dec 2023, 10:19
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anikpait17 wrote:
I got that the answer is A but everyone is ignoring D. I wanted to understand why?

Lets say There is a superior method than the current method to determine the ocean's age, it means that the earlier method that has been used for the same is inaccurate because we have a better method to ensure accuracy?

Having a "superior" method doesn't necessarily mean that the inferior method is inaccurate -- both methods could be quite accurate, but if one is slightly better, you'd have to call that one superior.

The superior method might also be superior for other reasons aside from accuracy -- maybe that method is easier, faster, or cheaper, for example.

Having a superior method wouldn't necessarily invalidate the argument, so (D) is not a required assumption.

I hope that helps!
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Re: The Earth's rivers constantly carry dissolved salts into its oceans. [#permalink]
16 Dec 2023, 10:19
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