## Ejemplo de Sentence Correction

The notion that it is possible to see the Great Wall of China from outer space loses credibility once it is made subject to a scientific criterion, since to be able to would be equivalent to be able to discern, at a distance of two metres, a single human hair on a background of similar colour.

- once it is made subject to a scientific criterion, since to be able to would be equivalent to be able to discern
- once that notion is subjected to scientific criteria, since to be able to do so would be equivalent to being able to discern
- once that notion is subjected with scientific criteria, since being able to do so would be equivalent to be able to discern
- once it is subjected to a scientific criterion, since to be able to do that would be equivalent to be able to discern
- once that notion is the subject of scientific criteria, since being able to would be equivalent to being able to discern

## Initial Solution

**Look down the list of beginnings.**You will observe that options A and D start with the words ‘once it is’ and that options B, C, and E begin with the words ‘once that notion is’.**Eliminate options A and D.**The referent of ‘it’ is not clear. Common sense tells you that this pronoun refers to ‘the notion’, but in grammatical terms it could refer to ‘outer space’, ‘the Great Wall of China’, or ‘the notion’.**Reserve option B.**There are no discernible mistakes.-
**Eliminate option C.**The phrase ‘is subjected with’ is idiomatically wrong: it should be ‘is subjected to’. -
**Eliminate option E.**The clause ‘once that notion is the subject of scientific criteria’ has no grammatical or idiomatic mistakes, but it has two major defects of another kind. First, it changes the meaning of the sentence.**This in not acceptable in the GMAT unless all the other options have grammatical or idiomatic mistakes, or mistakes of register.**And second, it expresses a very vague idea. How exactly can the notion that one can see the Great Wall of China become ‘the subject of scientific criteria’? The statement is almost meaningless.

B

## Subsequent Solution

The aim of the Initial Solution that has just been given is to outline the criteria that allow you to make quick and accurate eliminations. The Subsequent Solution that would follow it would contain a detailed description and analysis of all the other mistakes in the four incorrect options, and a comparison of those mistakes with the correct forms in option B. This is necessary because the GMAT constantly recycles errors: one that appears in a particular form in a certain question will very probably appear in another form in a different question. It is therefore in your interest to study the Subsequent Solutions in the Strategypractice Sessions in detail.

## Ejemplo de Problems Solving

On a certain road used by the same number of trucks as cars, the truck toll was 4 times the amount of the car toll. Then the truck toll was increased by 20 percent and the car toll was increased by 25 percent. If the number of trucks and the numbers of cars using the road remained the same, by what percent did the total amount of tolls collected from these vehicles increase?

- 21
- 21.5
- 24
- 24.5
- 45

A

Explanation:

We may plug in the following values: The road is used by just 1 car and 1 truck (for the number of cars and trucks must be equal). The car toll was $20 and the truck toll was $80 (for the truck toll was 4 times the car toll). So, the amount of tolls collected was 100 (in dollars). (This is a very convenient quantity if we want to calculate a percent variation on it). Then, the new car toll is $25 (an increase of 25% on $20) and the new truck toll is $96 (an increase of 20% on $80). So, the new amount of tolls collected is 25 + 96 = 121 (in dollars). Now, it is straightforward to conclude that the percent increase on the amount of tolls collected is 21%.

Therefore, the correct answer is A.