GMAT Data Sufficiency Answers
1) C. Recall that the sum of the 3 accounts is $3 million. If the largest is $1.3 million, then the sum of the other two accounts must be $1.7 million. Since the second-largest account could be $1.29 million, then the smallest account could be $0.41 million which is less than $0.5 million. Hence, Statement 1 by itself is insufficient. If we know the value of 2 of the variables and the average for all three, then we can determine the value of the third variable. If the largest is $1.3 million and the smallest is $0.7 million, then the third variable must be $1.0 million. With the value of all 3 variables, we can quickly determine the value of the smallest variable.
2) C. Statement 1 by itself is not sufficient because one of the two variables could be a small fraction. (Think of 500 and 0.01.) Statement 2 by itself could yield the product of 3 and 4. However, when both are taken together, we can definitively answer that this question can be answered “true”.
3) A. Statement 1 is sufficient to determine that x equals 5. Statement 2 only tells us that x could be +5 or -5.
4) E. Each statement is insufficient on its own to answer this question. To determine the percent change, we would need one of the pieces of additional information:
- The beginning stock price for the month.
- The ending stock price for the month.
- The percent change in the stock for the second half of the month.
5) A. There is only one combination of $20 and $30 items that will total $100 and that is two of each item. (It is OK to make the reasonable “real world” assumption that you can not have fractions when buying items in a mall.) The answer can not be C, because the second statement, by itself, could be interpreted to mean Al bought 3 $30 items and 1 $10 item for a total of zero $20 items.
6) E. The question can not be answered with the statements provided. The question is asking for the actual (dollar) increase and percents alone can not provide this. (It can be safely assumed in this type of problem that the test writers are not looking for the percent increase.)
7) E. The question can not be answered with the statements provided. If x is an even number, then it can be 2, which is a prime number. Statement 2 does not eliminate the possibility that x is an even number other than 2.
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