In GMAT, One of the popular strategies utilized by the test maker to confuse the test taker is to replace percentages with numbers and vice versa. The test taker becomes a victim of this trap if he is not well aware about the concept of percentage.
Percentage as the name indicates is per cent or per 100. So in the argument if it is stated that 14% of the test takers failed the author of the argument means to say that assuming that Hundred test takers appeared for the test fourteen of them failed to clear it . So if the number of test takers increases to 200 then the number of test takers who have failed in the test will proportionately increase to 28. It is clear from the previous discussion that 14% and 14 are not interchangeable.
But in case if the concept of percentages is not well understood then the test taker may not see the difference between the two entities and may fall into the trap beautifully laid by the test maker.
GMAT also utilizes the concept of Averages to good effect to befuddle the test taker. Average is mathematically defined as the sum total of all the observations divided by the total number of observations. So if the teacher says that the average height of boys in his class is 5 feet 4 inches, he doesn’t mean to say that every boy of his class is 5 feet 4 inches tall. Instead he means to say that the height of boys of his class is somewhere in the vicinity of 5 feet 4 inches and not exactly 5 feet 4inches.
In GMAT questions, the test maker generalizes the average of all the participants of the group to every individual participant of the group. The unaware test taker falls into this trap laid by the test maker.
So whenever you find that there is a shift from percentages to numbers in any given CR question be mindful of the trap discussed above and whenever you find that there is a attribution of the average of observations of a group to every individual member of the group be wary of the trap discussed in the last two paragraphs.