All oceangoing ships carry seawater ballast tanks whose weigh

I love this CR as this paragraph is related to my job that we do every now and then at sea after loading discharging.

Ballasting/ DeBallasting : Changing of water at deep sea to avoid migration of organism from one part of the world to another part ( apparently it caused a havoc in great lakes due to the inadvertent release of ballast water that contained predatory and harmful organisms into a different ecosystem).

So question at hand says: All oceangoing ships carry seawater ballast tanks whose weight improves stability. Notice that keyword is stability so you are required to have stability at all time of passage as well as at port.

Conclusion: One viable way of addressing this problem would be to empty and then immediately refill the tanks in midocean.

So assumptions required : 1 - There are no undue stress ( generally we do ballast exchange when seas are calm or somewhat moderate) and stability issues with the ship while doing ballast exchange.
2: After exchange we are not left with substantial number organism or organism which could multiply and later wreak havoc on ecosytem.

keeping this in mind lets analyse Answer choices.

A. Emptying and refilling an oceangoing ship's ballast tanks in midocean would ensure at least that no sea creatures capable of disturbing the ecology in a new habitat are
pumped into the tanks.This is not an assumption as negating it will not do anything.

B. An oceangoing ship's ballast tanks could be emptied and refilled in midocean only in conditions of calm air and flat seas.This only give a factor or working environment again not an assumption.[color=#00a651]

C.[color=#111111] Sea creatures have rarely if ever, wreaked ecological havoc in a new habitat, unless they have been able to survive in that habitat after having been deposited there by
oceangoing ships.this is not an assumption it is clearly stated in the passage
As a result, sea creatures often get into the tanks and are then inadvertently deposited into new habitats, where they can wreak ecological havoc.

D. Currently, seawater is pumped into or out of the ballast tanks of oceangoing ships to maintain proper stability only when unloading or loading cargo.[Not an assumption.

E. There are at least some oceangoing ships whose stability could be adequately maintained while emptying and refilling their ballast tanks in midocean.Ah! this is the same one we have mentioned in the assumption. So correct ans

So answer E

How E is the assumption can anyone please explain?

Posted from my mobile device

The word "atleast some " in option E prevented me from selecting this choice as I expected the assumption to hold true for all the oceangoing ships for this to be a viable solution. Please tell me why is my thinking not correct.
thanks:)

C is irrelevant.Why should anybody be bothered about what seacreatures generally do.The scope entails to thinknof sea creatures in ballast tanks.Good question

Posted from my mobile device

We are left with option C and E at best after solving this question.


This option says that sea creatures, if they survive in the habitat after having been deposited there by oceangoing ships, create havoc, otherwise they create havoc rarely.

But it is clearly mentioned in the argument that "As a result, sea creatures often get into the tanks and are then inadvertently deposited into new habitats, where they can wreak ecological havoc." Why should be then bothered about this option again??




This option directly deals with checking that can we really achieve stability of the ship, if we do the activity in midocean.
If we cannot do this activity in midocean, there is no point we can address the problem. This destroys the whole purpose of the argument.

E is correct

So if anyone sees this...so far I have been scoring about 63% on LSAT assumption questions. Is that decent for GMAT?

Option C provide additional information about the deposition of se creatures when they are dead. The original questions doesn't provide that information.

All oceangoing ships carry seawater ballast tanks whose weight improves stability. To maintain the ship's proper stability, water must be pumped out of these tanks when cargo is loaded and into them when cargo is unloaded. As a result, sea creatures often get into the tanks and are then inadvertently deposited into new habitats, where they can wreak ecological havoc. One viable way of addressing this problem would be to empty and then immediately refill the tanks in midocean, since midocean creatures and coastal sea creatures usually cannot survive in one another's habitats.

Which one of the following is an assumption the argument requires?

A. Emptying and refilling an oceangoing ship's ballast tanks in midocean would ensure at least that no sea creatures capable of disturbing the ecology in a new habitat are pumped into the tanks.

B. An oceangoing ship's ballast tanks could be emptied and refilled in midocean only in conditions of calm air and flat seas.

C. Sea creatures have rarely if ever, wreaked ecological havoc in a new habitat, unless they have been able to survive in that habitat after having been deposited there by oceangoing ships.

D. Currently, seawater is pumped into or out of the ballast tanks of oceangoing ships to maintain proper stability only when unloading or loading cargo.

E. There are at least some oceangoing ships whose stability could be adequately maintained while emptying and refilling their ballast tanks in midocean.

I was between A and E, picked A unfortunately for the reason that i did negation wrongly.
E is clearly the right answer as if negated it breaks passage apart - that NONE of the oceangoing ships could .... midocean.

A on the other hand if negated(wrongly as i did) looks like this:
1. Emptying and refilling an oceangoing ship's ballast tanks in midocean would NOT ensure that no sea creatures capable of disturbing the ecology in a new habitat are pumped into the tanks. - This is wrong way of negating
2. Emptying and refilling an oceangoing ship's ballast tanks in midocean would ensure at least that some sea creatures capable of disturbing the ecology in a new habitat are pumped into the tanks. - I believe this is the right way to negate.

Which one would you pick and why??

How is C incorrect? An underlying assumption to this Q would be that once mid-ocean creatures are deposited in Coastal areas, they don't wreak havoc in such an extremely short timeframe. (Can be that as soon as the mi-ocean fish enters the coastal region, it wreaks havoc)

Hi GMATNinja, Why is "E" a better answer than "A"? I have some bit of confusion here.

Could you please help?

Imagine that your ship unloads some cargo at a port, refills the tanks before leaving port, and in the process accidentally picks up some Seussian Dogfish, a (made-up) coastal sea creature.

Once the ship reaches the middle of the ocean, the tanks are emptied, releasing the Seussian Dogfish. According to the argument, the Seussian Dogfish will probably die (since coastal sea creatures usually cannot survive in a midocean habitat) and thus probably won't wreak ecological havoc.

But what if, going against the proposed solution, we dump some Seussian Dogfish at a DIFFERENT port thousands of miles away?

That would be a NEW habitat for the Seussian Dogfish. Since it's a COASTAL habitat, we don't have any reason to believe that the Seussian Dogfish will die. So the Seussian Dogfish might wreak ecological havoc in the new coastal habitat.

Are Seussian Dogfish "capable of disturbing the ecology in a new habitat"? Absolutely. Does that mean we have to AVOID pumping Seussian Dogfish into the tanks in order for the proposed solution to work? Nope. As long as we empty the tanks midocean, as suggested, the odds of havoc-wreaking are low.

So the argument works even if (A) is not assumed, which means it can't be our answer.

(E), on the other hand, is required. If there are NO oceangoing ships whose stability could be adequately maintained while emptying and refilling their ballast tanks in midocean, then the proposed solution isn't viable.

I hope that helps!

@gmatninja, @KARISHMA, @MARTYTTP can you please explain why option C is incorrect ?

This one is tough to get in 2 minutes

The conclusion, in essence, is that if ships empty and immediately refill their tanks midocean, sea creatures won't get into the tank and cause problems in new environments.

Take another look at (C):


Remember, this is an assumption question, so we're looking for something that has to be true in order for the logic of the argument to hold.

Why would it have to be true that sea creatures have rarely wreaked ecological havoc unless they were able to survive in a new environment after getting deposited there by ships? Couldn't sea creatures wreak havoc in other scenarios? Maybe they wreak havoc even though they don't survive very long in the new place. Maybe they wreak havoc after getting deposited by a different kind of vehicle, for example.

Put another way, it doesn't matter how often the problem of creatures ending up in new environments occurs in other scenarios. We know it's a problem with ships, because we're told this explicitly in the prompt. All we care about is whether this solution to the problem is, in fact, viable.

The punchline here is that (C) does not need to be true for the argument to hold, so it's wrong.

I hope that clears things up!