GMAT CR: “Strengthen” Question of the Day!

A broken shard of glass found in the laboratory of the famed physicist Alhazen has a polished surface that separates out the green and blue spectrums of white light, a key characteristic of a dispersive prism, which separates white light into all its constituent spectral components. Scientific historians, based on this finding, are revising their histories in order to give Alhazen, the “father of modern optics,” credit for the discovery of the dispersive prism, which was thought to have been discovered many years later.

Which of the following, if true, most strongly supports the historians’ decision to revise the history of optics?

A. Dispersive prisms were the only type of prism that was theorized about in the scientific era in which Alhazen lived.

B. The piece of glass from which the shard broke, if unbroken, would have been just large enough to separate out the entire spectrum of white light into its spectral components.

C. The piece of glass was a combination of flint glass, which was known to have been used by Alhazen to craft lenses in his laboratory, and crown glass, another popular type of glass throughout history.

D. Dispersive prisms are the simplest and most common objects that are able to divide white light into its constituent spectral components.

E. Several glass objects that are known to have some properties of a dispersive prism have been found to be older than the glass piece in Alhazen’s laboratory.


Conclusion: Historians give A credit for prism.

Evidence: Glass found that has characteristic of prism.

Assumption: Glass not there by accident; glass definitely means A “discovered” prism.

Question: What STRENGTHENS?

Prediction: Anything that links this glass to the prism, removes coincidence.

A – Other prisms out of scope.
B – This connects the glass to the prism.
C – The type of glass is irrelevant.
D – This is just a fact about the prism.
E – This would weaken, since it makes the glass/prism link less strong.

The answer is (B).


GMAT CR: “Resolve the Argument” Practice Question

In September of last year, the number of people attending movies in theatres dropped precipitously. During the next few weeks after this initial drop the number of film-goers remained well below what had been the weekly average for the preceding year. However, the total number of film-goers for the entire year was not appreciably different from the preceding year’s volume.

Which of the following , if true, resolves the apparent contradiction presented in the passage above ?

A) People under the age of 25 usually attend films in groups,rather than singly.
B) The gross income from box office receipts reamined about the same as it had been the preceding year.
C) For some portion of last year , the number of people attending movies in theaters was higher than it had been during the previous year .
D) The number of people attending movies in theaters rises and falls in predictable cycles .
E) The quality of films released in September and October of last year was particularly poor.


– In Sept, # of attendees dropped
– In Oct, # of attendees stayed below previous year’s weekly avg
– TOTAL number of filmgoers was not different from previous year

Question: How come?

Prediction: The months outside of Sept/Oct made up for the drop & allowed the year to remain consistent

A – irrelevant
B – irrelevant, we’re talking filmgoers not $$
C – boom, matches our prediction!
D – potentially, but more vague than C
E – irrelevant, we’re talking # of people not quality

Clearly it comes down to C and D. C is my choice since it most closely matches our prediction.

Learnist: Point of View in ACT Science questions

The key to better scores on the ACT Science Test Conflicting Viewpoints passages is to hunt down each author’s point of view. As you read each passage, look closely for keywords that help you identify the author’s opinions.

If there are multiple paragraphs, remember that the scientist or student usually uses the first few sentences to introduce his topic and start a discussion of the main idea. The final paragraph wraps up the discussion and reinforces the Main Idea. If you are having trouble finding what the overall point of view is for the passage, go back to the very beginning and the very end.

Don’t feel like you need a big background in Science to get Point of View or other Science questions correct. These are very close to Reading Test questions! Use these three tips:

  • Don’t Be Confused by the Extraneous Information
  • Cut Through the Scientific Jargon
  • Never Leave an Answer Blank

Try a few practice questions on this ACT Science: Point of View learnboard!

Tough GMAT: “Idiom” Sentence Correction – Problem of the Day!

Try this Idiom question from the Official Guide!

That educators have not anticipated the impact of microcomputer technology can hardly be said that it is their fault: Alvin Toffler, one of the most prominent students of the future, did not even mention microcomputers in Future Shock, published in 1970.

(A) That educators have not anticipated the impact of microcomputer technology can hardly be said that it is their fault
(B) That educators have not anticipated the impact of microcomputer technology can hardly be said to be at fault
(C) It can hardly be said that it is the fault of educators who have not anticipated the impact of microcomputer technology
(D) It can hardly be said that educators are at fault for not anticipating the impact of microcomputer technology
(E) The fact that educators are at fault for not anticipating the impact of microcomputer technology can hardly be said

Think of “that educators have not anticipated the impact of microcomputers technology” as one long noun. We could replace it with something like “This fact….” If we did that the original sentence would read:

This fact can hardly be said that it is their fault.

“that it is their fault” is incorrect. Something is “said TO BE” something, idiomatically. It would need to read, “can hardly be said TO BE their fault.”

Thus, A is eliminated.

E takes a different approach. If we replaced the full noun again with “this fact,” the sentence would read: “This fact can hardly be said.” This meaning is unclear. The focus is not that this fact literally can’t be said; the focus is that there are no grounds for saying the educators are at fault.

Looking at D, it makes it very clear what “can hardly be said” by neatly putting the noun-verb “educators are” after the “that.” Everything starting with “for…” is a long prepositional phrase that we could eliminate.

D would then read: “It can hardly be said that it is the fault of educators.” Clear, concise, logical. The correct answer is (D).

GMAT Problem of the Day: Drawing Conclusions on CR

This harder critical reasoning question requires us to draw our own conclusion based on information provided in the question-stem. Set a timer for 2 minutes, then dive in! Scroll down to check your work against my explanation!

At Legal Services, LLC last year, the average annual salary for attorneys was $75,000, while the average salary for paralegals was $50,000. The average annual salary for all Legal Services, LLC employees was $45,000.

If the information above is correct, which one of the following conclusions can properly be drawn on the basis of it?

A) There were twice as many attorneys at Legal Services, LLC as there were paralegals last year.
B) There were more paralegals than attorneys at Legal Services, LLC last year.
C) There were two attorneys and three paralegals at Legal Services, LLC last year.
D) There was at least one Legal Services, LLC employee who earned less than the average paralegal earned last year.
E) At least one paralegal made less than $50,000 last year.

Here’s how I broke it down:

Conclusion: Avg. annual salary for ALL employees was $45,000

Evidence: avg sal attorneys is $75,000, and avg. sal paralegals is $50,000

Assumptions: Average = Total Sum / # of terms, so the average of the attorneys and the paralegals together would be $60,000. Since the average salary is less than that, then there must be significant # of employees who are making less than $45,000.

Question Rephrase: What is TRUE based on the evidence?

Prediction: There must be some more poorly-paid employees.

The answer is (D).

(B) is incorrect because it does not HAVE to be true that there were more paralegals than attorneys. There could be the exact same number of paralegals as attorneys. What is weighting the average down to $45,000 is the fact that there is an unaccounted for number of employees making LESS than what the paralegals make.

How to Conquer Long Passages on the SAT

I’ll admit it- even I don’t love long SAT passages. These passages are no one’s favorite since it can be easy to get bored and confused by them, so let’s focus on some important strategies that will help you better understand the passages and get more questions correct!

When faced with one long SAT reading comp passage, it is especially important to take notes as you read. Make sure you underline the main idea of the paragraph and circle any important details. When you finish reading one paragraph, make sure you write down what the function of that paragraph was before moving on. The function should answer the question: why did the author write this paragraph? How does it fit into the whole passage? What’s its purpose?

Some common functions include: to introduce the topic, to support the topic, to introduce a new viewpoint, to bring in a counterargument, to provide an example, to describe a hypothesis, to offer an explanation, etc. A passage is simply the sum of its parts (in this case, its paragraphs). If you understand the parts, you’ll understand the whole. Think of each paragraph in terms of a verb and you’ll be on your way to answering those tough “The third paragraph serves primarily to…” questions. The key rule here: Don’t keep reading if you don’t understand why the author wrote the paragraph.

Another important tip to remember is to read the blurb! Many students overlook those few sentences and just dive right into the first paragraph, but it’s important to read the blurb first so you can understand the context of the passage. Often the blurb will tell you the purpose of the passage – the reason why the author wrote it. Is the passage a book review? Part of a novel or short story? An explanation of a scientific phenomena? Make sure you write down the purpose of the entire passage when you are done, before you answer questions!

A final tip to help you with the longest passages, besides noting the function/purpose and reading the blurb, is to pay attention to the author’s point of view and places where the author reveals opinion. How does the author feel about the topic? If this is a prose passage, how does the author feel about the characters? I like to write either a happy face or a sad face next to words that reveal opinion. For example, if the author described a character as “charming” and “clever,” I would put a smiley face next to those words. A quick glance to that paragraph later would remind me of the author’s opinion.

Let’s say we had a science-themed passage about hurricanes. Here is how our notes might look on this passage:

Para. 1: to introduce the topic of hurricanes – describe how powerful they are
Para. 2: to describe how a hurricane forms (☺- author v. interested in them)
Para. 3: to explain the history of hurricanes (where recorded; notable hurricanes)
Para. 4: to summarize how Hurricane Katrina happened
Para. 5: to recommend how hurricanes can be better detected/damage prevented
Para. 6: to explain how politics prevents this (low funding, etc.)

Overall Purpose: to describe how hurricanes form, their history & advocate more funding for their research

Ask yourself questions as you read and think critically to prevent even the most confusing and boring passages from distracting you from your goal!

GMAT CR: “Weaken” Question of the Day!

Try out this medium-level “weaken” question from GMAT Hacks!

Industry analysts feel that Bluecorp paid far too much to acquire rival fi…rm Strickland. While doing so limited competition they face in the marketplace, this approach cannot be pro…table in the long
run. Once two rival fi…rms merge in order to increase pro…ts, the higher prices would only provide other competitors an opportunity to enter the …field at a lower price, cutting into Bluecorp’s pro…fits
and making the acquisition of Strickland an expensive mistake.

Which of the following, if true, most seriously weakens the

(A) In some countries it is legal for two companies to merge
even if the resulting entity would nearly monopolize the

(B) The combination of Bluecorp and Strickland creates an
entity whose size allows it to produce items at a far lower
cost than could any smaller enterprise.

(C) In addition to eliminating competition, Bluecorp’s
acquisition gives it a much more substantial presence
in urban areas.

(D) As a result of the acquisition, the new corporate entity
will create two smaller entities to operate as independent
suppliers to Bluecorp.

(E) When two large companies in the same …field combine,
entrepreneurs tend to shy away from the fi…eld due to the
single entity’s perceived dominance.

-Conclusion: Bluecorp acquiring Strickland = NOT profitable long-term
(author concedes it DID limit competition)

-Evidence: Higher prices gives competitors opportunity

-Assumption: That the merger = higher prices

The question asks which answer choice would “weaken” the argument, so my prediction is something that shows the merger resulting in LOWER prices for Bluecorp.

Let’s look at the choices:

(A) The legality of the merger is irrelevant to the argument
(B) This correctly weakens the argument! “Lower cost” correctly refutes the “higher prices” in the assumption.
(C) Bluecorp’s presence in urban areas is irrelevant to the argument.
(D) Independent suppliers are irrelevant to the argument.
(E) The focus here is on the entrepreneurs “shying away” – it doesn’t weaken the argument, which focuses on the merger = higher prices.

The correct answer is (B).

Two Types of GRE “Averages”: Mean and Rates

The word “average” on the GRE can refer to two concepts: arithmetic mean, and the average speed (or average rate) formula. It’s important not to confuse the two on the Test Day, as they require different formulas to solve.

Mean is the mathematical average. This is defined as the sum of the terms divided by the number of terms. Mean = Sum / # of terms. For a list of consecutive integers or evenly spaced numbers, the mean is equal to the median, or the middle number. For example, the “average” of 3, 5, and 9 is 5.67.

Average Speed or Average Rate is often found in complex word problems. This type of question is one many students are less familiar with so you may not have seen it before. Let’s review two important equations to remember and look at how this concept appears on the GRE.

The first formula to memorize is: D = R x T. This stands for Distance = Rate x Time (referred to as the “DIRT” formula). It is perfectly acceptable to also think of it as Time = Distance / Rate or as Rate = Distance / Time as well. Usually the “Rate” is speed but it could be anything “per” anything. In a word problem, if you see the word “per” you know this is a question involving rates.

The second formula is: Average Rate = Total Distance / Total Time. This is its own special concept and you will notice that it is NOT a simple Average of the Speeds (which would be something like the Sum of the Speeds / the Number of Different Speeds or what we know as the Arithmetic Mean). Average Rate is a completely different concept, so do not let the common word “average” confuse you. Let’s look at a sample question from Grockit’s GRE question bank:

Question 1: The average (arithmetic mean) of four numbers is 30, after one of the numbers is removed, the average of the remaining three numbers is 10. What number was removed?

We know that the four original numbers sum to 30*4 = 120. The new equation becomes:

4*30 – x/3 = 10
120 – x/3 = 10
120 – x = 30 (add an x to each side and subtract a 30)
90 = x

Grammar Guide: The Difference Between a Hyphen and a Dash

Occasionally on the GRE or GMAT, you’ll see hyphens and dashes. How can you recognize them and use them properly?

There are two uses for a dash:

1. To indicate a break in thought.

Example: I forget which way to go- wait, now I remember!

Here the dash functions like a semicolon. Notice there is just ONE dash.

2. To set off a parenthetical phrase.

Example: My cousin Mary – whom you have never met – saw the movie “Gravity” last night.

Here the dashes function like commas setting apart non-essential information. Notice there are TWO dashes.

A hyphen and a dash look exactly the same, but are used differently:

Dash = Between words

Hyphen = Between syllables

Let’s look at an SC question involving this punctuation:

Archaeologists in Egypt have excavated a 5,000-year-old wooden hull that is the earliest surviving example of example of a “built” boat-in other words, a boat constructed out of planks fitted together-and that thus represents a major
advance, in terms of boat-building technology, over the dugout logs and reed vessels of more ancient vintage.

A. together-and that thus represents
B. together-and this has represented
C. together, and it represents
D. together that was representing
E. together to represent

Here, this dash is used correctly. The answer is (A).

The Most-Tested Grammar Rules on the SAT

For the SAT Writing section, the key to better scores is to familiarize yourself with the tested grammatical rules. Rather than read an entire book on English grammar, check out this list of the Top 10 grammar rules tested on the SAT!

1. Idioms. Idioms are expressions native to the English language. There are two part Idioms such as “neither…nor” and” between…and” as well as prepositional idioms like “interested IN” and “afraid OF.”

2. Run-ons & Fragments. These are two kinds of incomplete sentences. To be a complete sentence, a subject and a predicate verb is required. If either is lacking, the sentence is called a fragment. A run-on contains too much information, usually because two independent clauses (two complete thoughts) are being improperly combined.

3. Subject-Verb. The SAT loves to give long sentences where the main subject and the verb are separated by many words or clauses. You must identify the subject of each sentence and make sure the verb matches it in number. Generally, a plural noun takes a singular verb and a singular subject takes a plural verb.

4. Pronouns. The most common error associated with pronouns is pronoun-antecedent agreement. The antecedent is the word the pronoun is replacing. A pronoun must have a clear antecedent in the sentence; the lack of an antecedent is itself an error. The antecedent may often be present, but will disagree with the pronoun in number.

5. Parallelism. Parallelism is tested on the SAT in a series of phrases or items in a list. In parallel construction, the phrases or items must be in the same form. This can be tested with a number of parts of speech: nouns, verbs, prepositions, etc.

6. Modification. Modifiers are words and phrases that describe nouns. Adjectives, adverbs and modifying clauses will be incorrectly placed, or in the wrong form. Adverbs can only modify verbs, while adjectives modify nouns. Be on the lookout for suspicious adverb-noun and adjective-verb pairings. Also be aware that many sentences will begin with a modifying phrase and a comma. The subject after the comma must be the person or thing doing the action of the modifying phrase.

7. Comparisons. The SAT likes to compare similar things. People can only be compared to people, and things can only be compared to things. It also tests the comparative/superlative forms. Use better and more when comparing two things. Use best and most when comparing three or more things.

8. Wordiness. Wordiness means just what it sounds like, too many words! As long as there are no new grammar errors introduced, the shortest answer choice is often correct. Redundancy is a type of wordiness where the same thing is said twice. For example, the SAT would never call someone “intelligent and smart.” Keep it simple and to the point, and don’t repeat yourself!

9. Passive Voice. Passive Voice puts the object of the sentence first. Make sure to keep the subject (the person or thing doing the action) before the verb.

10. Diction. This is rarely tested on the SAT, so you are likely to only see 1-2 questions with this concept. Diction means “word choice.” The SAT may try to fool you by using a word that sounds similar to the intended word, but does not make sense in context (for example, replacing “imperious” with “impervious”). It’s important not to rush on the SAT.

Use this as a checklist to begin your studies. You’ll find articles for most of these tested areas right here on the GMAT Rockstar blog! As you study, focus on labeling each question with the “tested-concept” behind it. It’s not about getting every question correct individually, but learning to recognize the concepts. The questions will always change, but these concepts are guaranteed to show up on test day.