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Critical Reasoning - Useful to Evaluate Questions

Today, we will look at how to solve ‘useful to evaluate’ questions. Arguably, they are one of the toughest question types, perhaps right after boldface questions. To solve them, you follow these simple steps:

 

1. Identify the conclusion.

2. Ask yourself the question raised by option (A).

3. Answer it with a ‘yes’ and figure out whether it affects the conclusion.

4. Answer it with a ‘no’ and figure out whether it affects the conclusion. 

5. Repeat it for all other options.

6. There will be only one option which will affect the conclusion differently in the two cases. That is your answer. 

 

Let’s illustrate this with a problem: 

 

Question: In a certain wildlife park, park rangers are able to track the movements of many rhinoceroses because those animals wear radio collars. When, as often happens, a collar slips off, it is put back on. Putting a collar on a rhinoceros involves immobilizing the animal by shooting it with a tranquilliser dart. Female rhinoceroses that have been frequently recollared have significantly lower fertility rates than uncollared females. Probably, therefore, some substance in the tranquilliser inhibits fertility. 

 

In evaluating the argument, it would be most useful to determine which of the following? 

 

(A) Whether there are more collared female rhinoceroses than uncollared female rhinoceroses in the park. 

 

(B) How the tranquilliser that is used for immobilizing rhinoceroses differs, if at all, from tranquillisers used in working with other large mammals 

 

(C) How often park rangers need to use tranquilliser darts to immobilize rhinoceroses for reasons other than attaching radio collars 

 

(D) Whether male rhinoceroses in the wildlife park lose their collars any more often than the park’s female rhinoceroses do 

 

(E) Whether radio collars are the only practical means that park rangers have for tracking the movements of rhinoceroses in the park

 

Solution: First, we need to break down the argument to find the premises and the conclusion.

 

- Many rhinoceroses wear radio collars.

- Often, collars slip.

- When a collar slips, the animal is shot with a tranquilliser to re-collar.

- Fertility of frequently recollared females << fertility of uncollared females.

 

Conclusion: Some substance in the tranquilliser inhibits fertility.

 

Let’s take a look at each option.

 

(A) Whether there are more collared female rhinoceroses than uncollared female rhinoceroses in the park 

 

Yes, there are more collared female rhinoceroses than uncollared females. This does not affect the conclusion. This option talks about collared females vs uncollared females. We are comparing the fertility of recollared females with uncollared females. Anyway, how many of either type there are doesn’t matter. So whether you answer ‘yes’ or ‘no’ to this question, it is immaterial. 

 

(B) How the tranquilliser that is used for immobilising rhinoceroses differs, if at all, from tranquillisers used in working with other large mammals

 

Very different - This option is comparing the tranquillisers used for rhinoceroses with the tranquillisers used for other large mammal. What the conclusion does is compare collared female rhinoceroses with uncollared female rhinoceroses. Hence, whether you answer “very different” or “not different at all” - it doesn’t matter.

 

(C) How often park rangers need to use tranquilliser darts to immobilise rhinoceroses for reasons other than attaching radio collars 

 

Very often - Tranquillisers are used very often for uncollared females too. In that case, can we still say that “tranquilliser inhibits fertility”. No! If they did, fertility in uncollared females would have been low too.

Rarely - This would strengthen our conclusion. Tranquillisers are not used in case of uncollared females. So it is possible that something in tranquillisers inhibits fertility.

 

(D) Whether male rhinoceroses in the wildlife park lose their collars any more often than the park’s female rhinoceroses do 

 

More frequently - This option is comparing the frequency of tranquillisers used for male rhinoceroses with the frequency of tranquillisers used for female rhinoceroses. What the conclusion does is compare collared female rhinoceroses with uncollared female rhinoceroses. Hence, whether you answer “more frequently” or “no more frequently” - it doesn’t matter. 

 

(E) Whether radio collars are the only practical means that park rangers have for tracking the movements of rhinoceroses in the park

 

There are other means - This option is comparing radio collars with the other means of tracking. What the conclusion does is compare collared female rhinoceroses with uncollared female rhinoceroses. Hence, whether you answer “there are other means” or “no other means” - it doesn’t matter. 

 

Note that only option (C) affects the conclusion. If you answer the question it raises differently, it affects the conclusion differently. Hence, option (C) would be good to know to evaluate the conclusion. So answer must be (C).

 

Hope you will find this post useful to evaluate the “useful to evaluate” questions!

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