DATA SUFFICIENCYData Sufficiency is the type of GMAT quant question which tests the ability to understand and analyze the relevancy of information and decide at what point there is enough data to solve a problem.
Example – In a certain year, the difference between Mary’s and Jim’s annual salaries was twice the difference between Mary’s and Kate’s annual salaries. If Mary’s annual salary was the highest of the 3 people, what was the average (arithmetic mean) annual salary of the 3 people that year?
1. Jim’s annual salary was $30,000 that year.
2. Kate’s annual salary was $40,000 that year.
We will use linear equations rather than averages to solve this question in just 30 seconds and that too without any need of statements. The given information says that M-J=2(M-K) and in other words, it shows M=2K-J. By substituting this in the original equation, the average is 2K-J+J+K/3=3K/3=K
This means, from the information provided, we can conclude that just Kate’s salary is enough to answer this question. We have easily arrived at this answer without taking the data in the individual statements. Therefore, our answer is Option B.