November 12th, 2009 | 
Author: Last Tuesday a trucker paid $155.76, including 10 percent state and federal taxes, for diesel fuel. What was the price per gallon for the fuel if the taxes are excluded?
(1) The trucker paid $0.118 per gallon in state and federal taxes on the fuel last Tuesday.
(2) The trucker purchased 120 gallons of the fuel last Tuesday.
Highlight to see answer: D
Please post your explanations in the comments below!
If * represents a digit in the 7-digit number 3, 62*, 215, what is the value of *?
(1) The sum of the 7 digits is equal to 4 times an integer.
(2) The missing digit is different from any of the other digits in the number.
Highlight to see answer: C
Please post your explanations in the comments below!
If x and y are consecutive odd integers, what is the sum of x and y?
(1) The product of x and y is negative.
(2) One of the integers is equal to –1.
S is a set of integers such that
i) if a is in S, then –a is in S, and
ii) if each of a and b is in S, then ab is in S.
Is –4 in S?
(1) 1 is in S.
(2) 2 is in S.
There are two different types of data sufficiency questions: one asks if there is sufficient information to determine the answer for a yes/no question, and one asks if there is sufficient information to determine the answer to a numerical question. Questions that ask for yes/no answers typically require a thorough understanding of fundamental math rules, while numerical questions will ask require a bit of calculation. It’s important to make the distinction between the two problem types because time is very limited on the exam, and it is easy to get sucked in to performing clock draining unnecessary calculations.
It’s also important to distinguish between yes/no and numerical question types to avoid careless errors. Data sufficiency questions will often ask for a yes/no answer, and it will provide a statement that requires a bit of calculation. You will obtain a “no” answer based on the statement, and this will tempt your gut instinct to write “no” because the answer to the statement is “no.” But remember, we aren’t concerned whether the answer to each statement is “yes” or “no,” all we are concerned with is determining if the information provided is sufficient, which in this case is “yes.” This is best explained in an example.
Posted in Data Sufficiency, Updates | 
Tags: Data Sufficiency, gmat, gmat guide, gmat prep, gmat review, gmat test, numerical questions, yes/no | 
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