1) B.  No matter which number you roll the first time, you simply have to roll that second number again. Hence the correct answer is 1/6.

2) C.  Recall what we stated about not getting bogged down with complicated or lengthy calculations. The GMAT will never include haphazardly-determined numbers in its questions. The shortcut to this problem is that 1,320 is exactly one quarter of 5,280.

From reviewing your basic geometry, you will know that circumference=2>πr which in this scenario means that the circumference of this circle is 20π where the unit of measurement is feet. This can be converted to miles very easily and we can quickly ascertain that the blade travels 20π(1/4) miles per second. This equals 5π miles per second. Over 60 seconds, the tip of the blade will travel 300π miles.

Note: Keep in mind this is a math problem and shares many similarities to the questions you will encounter on the GMAT. We were informed by an engineer that at the rate of speed the hypothetical propeller travels, the “the hub would certainly explode and the prop tips would have already been melted off from the intense heating”. Well, we’ll admit we’re not engineers and his statement may indeed be correct. Our point remains that you do not want to get caught up in such nuances, especially since the GMAT test writers are not likely to include pilots or engineers either.

3) D.  This is an example of a common GMAT graph problem where you will have to rely on your visual interpretation of the graphs. Indeed, the units sold by Charlotte and Dennis are 150 and 50, respectively. Armed with this data, we know that 500 total units were sold and Alison sold 20% of these. The right answer is not 20, however, as the question asked for the number of degrees the angle represented. Since there are 360 degrees in a circle, the correct answer is 72.

4) B.  This question requires that you be acquainted with the principles of algebra. You can also solve this backwards by assigning a value to a and then solving for b and a*.

5) D.  This word question can be easily solved in one of two ways. You can solve for Tim’s age today by constructing the following two equations where T = Tim’s age today and S = Susie’s age today:

1. T = 2S
2. T – 2 = 3(S – 2)

You can also solve this problem by working backwards.

6) E.  This problem is most efficiently answered by employing process of elimination. Choice A is not evenly divisible by 2. Choice B is not evenly divisible by 5. Choice C is not evenly divisible by 4. (The last two digits, 30, are not divisible by 4.) Choice D is incorrect because it is also divisible by 9. (The sum of its digits equals 18 which is divisible by 9.) Choice E is left through this process of elimination. You can double check this by noting that the sum of its digits equal 21 which is divisible by 3, but not by 9. It is also meets the criteria for being equally divisible by 2, 4, and 5.