Why You Need Pacing Benchmarks on Quant

The Quant section contains 31 questions in 62 minutes. That is exactly 2 minutes per question!

How can we complete the sections with so little time? By knowing how the exam is scored and using that knowledge to our advantage!

Some tips:

95% of test-takers don’t have time to attempt every Quant question. With only 2 minutes/question on the Quant section, the GMAT purposefully does not provide you with adequate time. Don’t be fooled into thinking you must attempt every question. In fact, unless you are preternaturally fast with very high Quant accuracy, you should NOT be attempting every question!

Always look at the answer choices first in Problem Solving. On the GMAT Quant section, we’re looking for the fastest (and easiest) way to get through the problem. You’ll need to be flexible, and learn how to Approximate, Pick Numbers, Backsolve, and Guess Strategically. Yes, Algebra may be your go-to for most problems, but you will become faster the more flexible you are.

Every time your take a practice test, write out these above numbers on a sheet of paper. Have them on your desk so you can get used to “checking in” every 5 questions. Do not try to “memorize” these benchmarks right now. Though you probably will memorize them eventually just out of habit, on your first few CATs the visual aid will help you remember to check-in.

Bringing more awareness to how you “pace out” the Quant section will help you fight “test day panic” enormously! It often takes students 5-6 practice exams before they “get the hang” of how to deal with pacing. Be patient with yourself, and be a little more free with “throwing away” questions. Most students find their score jumps 50+ points once they have the pacing under control.

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Compound Interest: a Sequence in Disguise?

A man invested $P in a long term investment plan for 24 years at an interest compounded annually. Due to some financial crisis he had to withdraw money at the end of 6 years. How much more amount could be have gotten after 24 years if he received $3P after 6 years. It is known that there were no other charges of deduction in the plan?

A) 9P
B)24P
C)72P
D)78P
E)81P

This question is tricky at first since we don’t know the compounding interest rate, and feels like perhaps we would need a compound interest formula to solve, but let’s consider.

It started at P and then compounded 6 times and tripled itself to 3P. So this is more like a Geometric sequence question!

The rule is “P triples every 6 years.”

Year 1 – P
Year 6 – 3P
Year 12 – 9P
Year 18 – 27P
Year 24 – 81P

How much more means we subtract 3P from 81P:
81P-3P = 78P

The answer is (D). This is an interesting question — a sequence in disguise!

Why Scope Matters in CR Assumption

Let’s look at this CR Assumption question (it’s actually an LSAT question, but let’s give it a whirl):

In considering the fact that many people believe that promotions are often given to undeserving employees because the employees successfully flatter their supervisors, a psychologist argued that although many people who flatter their supervisors are subsequently promoted, flattery generally is not the reason for their success, because almost all flattery is so blatant that it is obvious even to those toward whom it is directed.

Which one of the following, if assumed, enables the psychologist’s conclusion to be properly drawn?

Evidence: 
-Belief that flatterers get undeserving P
-Many who flatter get P

Notice here the 2nd sentence is split between evidence and conclusion. The “real conclusion” doesn’t start until “because almost all…” This happens quite often and can be confusing to students who often wonder which clause is the conclusion.

Conclusion: 
As with all Assumption questions, we have to look for the brand-new, sparkly keywords in the Conclusion — the “concept-shift,” or the new idea that appears in the conclusion that appears to “come out of nowhere.” Here it is this new idea about it being “blatant” or “obvious.”

Concept Shift: “flattery…obvious”

Why does it matter if the flattery is obvious to the supervisors? There is clearly an assumption made here that whether the supervisors KNOW they are being flattered has an impact.

The scope of the correct answer needs to be on the awareness of the supervisors.

Prediction: If supervisors know they are being flattered, they wouldn’t promote undeserving employees b/c of it.

Let’s look at the scope of each answer choice:

(A) People in positions of responsibility expect to be flattered. (scope: Expectations of Supervisors)
(B) Official guidelines for granting promotion tend to focus on merit. (scope: Official guidelines)
(C) Flattery that is not noticed by the person being flattered is ineffective. (scope: Effectiveness of Flattery)
(D) Many people interpret insincere flattery as sincere admiration. (scope: Misinterpretation of Flattery)
(E) Supervisors are almost never influenced by flattery when they notice it. (scope: Supervisors and Flatter)

At this point, because of our prediction, it should be very clear the answer is (E), with (D) as our second-best (but still wrong). Identifying that “concept shift” and getting crystal-clear on what kind of scope you expect the correct answer to focus on will REALLY help your Assumption-spotting abilities.

Just because we’re here, let’s look in more detail at the answer choices:

(A) Whether supervisors EXPECT to be flattered has no bearing on whether promotions occur as a result of it.

(B) What official guidelines DO or DON’T say has zero stated relationship in the passage to the ACTIONS of supervisors.

(C) This is trickier. It basically says that Unnoticed Flatter is Ineffective. Okay…but we cannot assume that Flatter that is noticed IS effective. And even if we could, that would Weaken the argument, not be its Assumption.

(D) Just because MANY people think flatter is sincere, doesn’t mean SUPERVISORS do, and it doesn’t follow therefore that the supervisors would promote flatterers just because they think they are sincere. This choice essentially just says, “Some people are dumb.” Well…okay, but what does that have to do with the idea of supervisors and promotions?

(E) If we negate this choice, we can see even more why it is correct.

Negation of (E): Supervisors ARE influenced by flattery when they notice it.

Well, if they ARE, then the author’s entire conclusion that flattery is not the reason for the success kind of falls apart!

Things the GMAT Does Not Like: “Because of” + NOUN + -ing

becauseSince the word “of” is a preposition, when we add it behind “Because” it limits what we can have afterwards to a noun.

On the GMAT, “Because” and “Because of” are NOT interchangeable!!!

We use “Because” to describe an entire clause. For example:

CORRECT: Because Ft. Sumter was attacked, the Civil War began.

The bold section (everything between the “Because” and the comma, is an independent clause and could stand on its own as a complete sentence. The word “Because” is describing that entire action. BECAUSE this action occurred, something else occurred.

Let’s look at the sentence if we tried to use “Because of” instead of “Because”:

INCORRECT: Because of  Ft. Sumter was attacked, the Civil War began. 

Hopefully you can hear just how “wrong” that sounds! If we’re describing an entire action and using an independent clause, we need only “Because.”

“Because of” should describe a NOUN only. 

CORRECT: Because of his complete lack of remorse, the criminal was given a harsher sentence.

“His complete lack of remorse” is a noun phrase, so “Because of” is used correctly.

One thing the GMAT does not like is sentences that attempt to use “Because of” + NOUN + an “-ing” verb. This construction is incorrect, since, as we have seen, “Because of” is best used with just a noun.

Example: “Because of the Senator attending the event …” = WRONG!
Example: “Because of the girl winning the sports competition…” = WRONG!
Example: “Because of Alex getting a 700 on the GMAT…” = WRONG!
Example: “Because of the cat sleeping all day…” = WRONG!

We would want these ideas to be expressed with just “Because,” and change the verb to make logical sense:

Example: “Because the Senator is attending the event,…” = RIGHT!
Example: “Because the girl had won the sports competition…” = RIGHT!
Example: “Because Alex got a 700 on the GMAT…” = RIGHT!
Example: “Because the cat had slept all day…” = RIGHT!

Let’s look at a practice question that uses this structure:

Because of the broker having a portfolio of losses, he will most likely be let go from the firm.

(A) Because of the broker having
(B) Because of the broker having had
(C) Because the broker having had
(D) Because the broker has
(E) Because of the broker had been having

(A) and (B) both attempt to put the participle (-ing) verb immediately after the noun “the broker.” The GMAT does not approve of this! Therefore, (A) and (B) are incorrect.

(E) is also incorrect (not least of all because its verb tense makes no sense).

Only (C) and (D) are options. They now use “Because” so what follows must be an independent clause. Let’s examine both sentences, and highlight the section between the “Because” and the comma:

(C) Because the broker having had a portfolio of losses, he will most likely be let go from the firm.
(D) Because the broker has a portfolio of losses, he will most likely be let go from the firm.

Only (D) puts something that could stand on its own as a complete sentence after the “Because.” Therefore, the correct answer is (D).

 

 

Arithmetic and the GMAT

Random pile of colourful plastic lettersThe branch of mathematics dealing with the basic manipulation of numbers is called “arithmetic.” On the GMAT, Arithmetic questions have to do with solving equations and expressions by moving variables from one side of the equation to the other.

Sometimes this involves conversion, or describing one variable in terms of another. Let’s look at an example from the OG:

Temperatures in degrees Celsius (C) can be converted to temperatures in degrees Fahrenheit (F) by the formula F = 9/5*C + 32. What is the temperature at which F = C?

(A) 20°
(B) (32/5)°
(C) 0°
(D) -20°
(E) -40°

Explanation

The question is asking what is the temperature at which F = C. For this question if, F = C, then wouldn’t F = (9/5)C + 32 be the same thing as C = (9/5)C + 32?
If C = (9/5)C + 32, we can start to simplify by subtracting (9/5)C from both sides.
C – (9/5)C = 32 is the same thing as:
(9/9)C – (9/5)C = 32
(-4/5)C = 32

Let’s multiply both sides by 5:

-4C = 160
C = -40

The correct answer is (E).

Factorials (!) and Divisibility

exclamationIt’s amazing how something as simple as a (!) symbol can throw us all for a loop, even when really we’re just looking at a very simple divisibility question. This is my own question designed to mimic a GMATPrep question.

Start by setting a timer for 2-minutes and try this one on your own, then scroll down for the explanation!

Which of the following is an integer?

I. 10! / 3!
II. 9! / 8!
III. 13! / 11! 5!

A) I only
B) II only
C) III only
D) I and II only
E) I, II, and III

Explanation:

If the result of a fraction is an integer that means that what is in the denominator divides evenly into what is in the numerator. The question for each of these Roman numerals becomes: will the denominator go evenly into the numerator?

Since we know that 10! = 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1, and 3! = 3 x 2 x 1, it is obvious that the denominator of Roman Numeral 1 will go evenly into its numerator.

This same logic can be applied with Roman Numeral 2. As long as the factorial in the numerator is larger than the factorial in the denominator, then we will get a resulting integer.

Roman Numeral 3 is more complex. If we start by cancelling out the 11! from both the numerator and the denominator, the resulting fraction becomes:

(13 x 12) / (5 x 4 x 3 x 2)

Since 4 x 3 = 12, we can cancel those values out:
13 / (5 x 2)

Now we are stuck. 13 is a prime number, so neither 5 nor 2 will divide evenly into it. The result will be a decimal.

The correct answer is (D).

 

CR Weaken: Why We Need to be Flexible

With Weaken questions, we need some flexibility with the answer choices, since there are several ways to weaken an argument:

-Provide an explanation
-Prove the assumption is wrong
-Undermine a piece of evidence

I find the easiest “default” for a Weaken prediction is to identify the Evidence, Conclusion, and Assumption of the argument, and then simply reverse the assumption.

The hard part is trying to do all of this in your head, so I HIGHLY suggest you do all CR work on your scratch pad. No need to write the entire argument down. You can easily summarize it with abbreviations and symbols. Let’s examine a question:

Microbiologist: A lethal strain of salmonella recently showed up in a European country, causing an outbreak of illness that killed two people and infected twenty-seven others. Investigators blame the severity of the outbreak on the overuse of antibiotics, since the salmonella bacteria tested were shown to be drug-resistant. But this is unlikely because patients in the country where the outbreak occurred cannot obtain antibiotics to treat illness without a prescription, and the country’s doctors prescribe antibiotics less readily than do doctors in any other European country.

Which of the following, if true, would most weaken the microbiologist’s reasoning?

A) Physicians in the country where the outbreak occurred have become hesitant to prescribe antibiotics since they are frequently in short supply.
B) People in the country where the outbreak occurred often consume foods produced from animals that eat antibiotics-laden livestock feed.
C) Use of antibiotics in two countries that neighbor the country where the outbreak occurred has risen over the past decade.
D) Drug-resistant strains of salmonella have not been found in countries in which antibiotics are not generally available.
E) Salmonella has been shown to spread easily along the distribution chains of certain vegetables, such as raw tomatoes.

Here, the evidence tells us a prescription is hard to get, so antibiotics aren’t to blame for the salmonella, even though the salmonella were drug-resistant.

The bad logic here is that the author is assuming there isn’t ANOTHER way that antibiotics could have caused the salmonella, just because doctors don’t give out prescriptions.

So, to weaken, let’s reverse the assumption: what if there was ANOTHER way that the antibiotics contributed to the salmonella that didn’t involve doctors???

Notice that once we’re crystal-clear on the argument, the correct answer is much easier to spot.

B) is saying the salmonella could have come from people eating animals who eat antibiotics. Maybe it transferred?

This is a solid option, and a good reversal of the assumption.

Many students, however, will eliminate (B) right off the bat, because they will think, “huh, I didn’t read anything about “animals that eat antibiotics-laden livestock feed.” But remember, Weaken questions can be exceptionally difficult, and since there is more than one way to weaken, we have to be open to the idea that the correct answer may introduce a detail that at first seems totally irrelevant, but after a few seconds reveals itself as something that destroys the conclusion.

The author said it is “unlikely” that antibiotics could be blamed BECAUSE of the doctors not giving prescriptions.

BUT, if the people are getting antibiotics from a totally different source, then yes, the antibiotics could still be blamed.

Here is how our analysis could have looked for this question on our scratch pad:

weaken1

Remember to make a prediction for a “Weaken” question on your scratch pad, but ALSO be open to the idea that the correct answer might weaken the argument in an unexpected way!