Diez preguntas del banco del curso
Las diez preguntas siguientes están tomadas, sin cambios, del banco de práctica de Seeking English: 1,000 preguntas del GMAT Focus Edition con explicación, el porqué de cada opción incorrecta y la trampa típica de cada pregunta. El banco completo está incluido en la cuota del curso GMAT. Elegimos cuatro de Problem Solving, tres de Critical Reasoning, dos de Data Sufficiency y una de Two-Part Analysis, todas de nivel básico o medio.
Quantitative Reasoning
1. A hat contains 5 tickets, numbered 1 through 5. Two tickets are drawn at random, one after another, without the first ticket being returned to the hat. What is the probability that both tickets drawn show even numbers?
Explanation. Of the 5 tickets, 2 are even (2 and 4). The probability the first ticket drawn is even is 25. Since the first ticket is not replaced, only 4 tickets remain for the second draw, of which 1 is even, so the second-draw probability is 14. Multiplying gives 25×14 = 110.
Trap: treating a without-replacement draw as though the first item were replaced.
2. How many integers x with 1≤x≤15 satisfy − 3x + 4> − 17?
Explanation. Subtracting 4 gives − 3x> − 21. Dividing by − 3 reverses the inequality: x<7. Within 1≤x≤15, the integers 1 through 6 satisfy this, so there are 6.
Trap: forgetting to reverse the inequality when dividing by a negative number, a sign error moving the constant, or misreading the inequality as non-strict.
3. What is the units digit of 612 + 415?
Explanation. Every power of 6 ends in 6, since 6×6 = 36 always returns to units digit 6. Powers of 4 alternate in a cycle of length 2: 4, 6, 4, 6, and so on, so an odd exponent like 15 gives units digit 4 (matching 41 = 4) while an even exponent would give 6. Adding the two units digits, 6 + 4 = 10, so 612 + 415 itself ends in 0.
Trap: dropping one of the two terms, mixing up the parity rule for the alternating base, or slipping in the final addition.
4. A tailor buys fabric for an order: 6.5 meters of wool fabric at 8.4 dollars per meter, and 3.25 meters of linen fabric at 5.6 dollars per meter. What is the total cost of the order, in dollars?
Explanation. Wool costs 6.5×8.4 = 54.6 dollars and linen costs 3.25×5.6 = 18.2 dollars. The order total is 54.6 + 18.2 = 72.8 dollars.
Trap: applying one item's rate to both quantities, or combining rates before multiplying.
Verbal Reasoning
5. Bramwell Coffee launched a loyalty program that gives a free drink after every ten purchases. Store managers claim the program will increase the average number of visits per customer per month.The answer to which of the following questions would be most useful to know in evaluating the argument above?
Explanation. The claim is that the program will raise visit frequency. If enrolled customers are visiting more often than before, the claim is supported; if their visit frequency is unchanged, the claim fails. Every other choice leaves that question untouched.
Trap: a cost or popularity question mistaken for a test of the stated claim.
6. Bellwood Foods recalled one batch of its canned soup after a labeling error was discovered. In the following quarter, the company's total soup sales were higher than in the quarter before the recall.Which of the following, if true, would best explain the finding?
Explanation. A recall would normally be expected to depress sales, at least briefly, yet Bellwood Foods' total soup sales rose the following quarter. New, well-received flavors launched in that same quarter supply a growth driver strong enough to outweigh any dent from the recall, accounting for both the recall and the higher total. Noting that the recalled batch was a small share of production only limits the potential damage; it does not supply a reason sales increased.
Trap: explaining why the recall's damage was limited instead of explaining the increase itself.
7. The town of Bellrose banned single-use plastic bags at retail stores. In the year after the ban, the amount of plastic litter collected during the town's quarterly cleanups fell by nearly half. A town council member argues that the bag ban caused the drop in plastic litter.Which of the following, if true, most strengthens the council member's argument?
Explanation. The argument needs the ban, not some other behavior, to explain less litter. Confirming that customers switched to reusable rather than other disposable bags shows the banned item was actually removed from use rather than merely replaced by another disposable one.
Trap: confirming that behavior shifted away from the banned item entirely.
Data Insights
8. A bag contains only red marbles and blue marbles. If one marble is drawn from the bag at random, what is the probability that the marble drawn is red?(1) The probability that the marble drawn is blue is 0.35.
(2) The bag contains 26 red marbles.
Explanation. Statement (1) alone: since every marble is either red or blue, the probability of red is exactly 1 − 0.35 = 0.65, a single value regardless of how many marbles are in the bag. Sufficient. Statement (2) alone, with statement (1) covered: knowing the number of red marbles without knowing the total number of marbles leaves the probability open — 26 red marbles out of 40 total gives a probability of 0.65, while 26 red marbles out of 100 total gives a probability of 0.26. Not sufficient. Since statement (1) alone pins the probability and statement (2) alone does not, the answer is A.
Trap: the hidden A, from not applying the complement rule to a two-outcome situation.
9. At a certain theater, did the number of tickets sold on Saturday exceed the number sold on Friday?(1) The theater sold 340 tickets on Friday.
(2) The theater sold 15 percent more tickets on Saturday than on Friday.
Explanation. Statement (1) alone: knowing Friday's count alone, with nothing said about Saturday, leaves the comparison completely open. Not sufficient. Statement (2) alone, with statement (1) covered: if Saturday's total is 15 percent more than Friday's, then Saturday's total equals 1.15 times Friday's, and 1.15 times a positive ticket count is always more than that count, whatever it was. So Saturday's count exceeds Friday's regardless of Friday's actual value — a definite yes. Sufficient. Since statement (2) alone gives an invariable answer and statement (1) alone does not, the answer is B.
Trap: the C trap, from assuming a percent comparison needs a base value to be meaningful.
A company has 60 employees split between two departments, Sales and Support, in the ratio 3 to 2 (Sales to Support).
Select the number of employees in Sales, and select the number of employees in Support. Make only one selection in each column.
| Number of employees in Sales | Number of employees in Support | |
|---|---|---|
| 12 | ||
| 24 | ||
| 30 | ||
| 36 | ||
| 48 |
Explanation. The ratio 3 to 2 splits 60 employees into 3 + 2 = 5 parts, so each part is 60÷5 = 12 employees. Sales holds 3 parts, or 3×12 = 36 employees, and Support holds 2 parts, or 2×12 = 24 employees. Check: 36 + 24 = 60.
Trap: even split instead of applying the stated ratio.
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Si te interesa el banco completo (990 preguntas más, incluidos los niveles 4 y 5, Reading Comprehension, Table Analysis, Graphics Interpretation y Multi-Source Reasoning), viene incluido con el curso GMAT de Seeking English, junto con las clases en vivo y la revisión de simulacros. También puedes hacer el test corto de seis preguntas, que cubre las tres secciones.
Un ejemplo de cada formato
Doce preguntas escritas por nosotros al estilo del examen, una por cada formato que vas a encontrar, incluidos los que el bloque anterior no cubre: Reading Comprehension, Table Analysis, Graphics Interpretation y Multi-Source Reasoning. La respuesta está oculta hasta que la abras; intenta cada una con cronómetro antes de mirarla.
Quantitative Reasoning
Problem Solving · arithmeticA store marks a coat down by 20 percent and then takes a further 25 percent off the already reduced price. What percent of the original price does the customer pay?
- 45%
- 55%
- 60%
- 65%
- 75%
Problem Solving · number propertiesIf n is a positive integer and n2 is divisible by 24, what is the largest integer that must divide n?
- 2
- 4
- 6
- 12
- 24
Problem Solving · work ratesMachine A fills a tank in 6 hours and machine B fills it in 3 hours. They start together, and A is switched off after 1 hour. How long does it take in total to fill the tank?
- 2 h
- 2 h 15 min
- 2 h 30 min
- 2 h 45 min
- 3 h
Rates add; times do not. Always work in "fraction of the job per hour".
Problem Solving · statisticsThe average (arithmetic mean) of five numbers is 20. If the largest number is removed, the average of the remaining four is 15. What was the number removed?
- 25
- 30
- 35
- 40
- 45
Verbal Reasoning
Critical Reasoning · weakenA city council argues that widening Main Street will reduce traffic congestion downtown, because the two other streets that were widened last year now carry more cars per hour than before. Which of the following, if true, most weakens the argument?
- Main Street is longer than either of the two streets widened last year.
- The two widened streets now attract drivers who previously used other routes, and total downtown travel time has not fallen.
- The widening project on Main Street would take fourteen months to complete.
- Some residents of Main Street oppose the project.
- Public transit ridership downtown fell slightly last year.
In weaken questions, find the unstated premise (here: "more flow = less congestion") and the option that denies it.
Critical Reasoning · assumptionCompany X's sales rose 30 percent in the quarter after it began advertising on streaming platforms. Therefore, streaming advertising is an effective way for Company X to raise sales. The argument depends on which assumption?
- Company X's competitors do not advertise on streaming platforms.
- The 30 percent increase was not primarily caused by factors other than the streaming campaign.
- Streaming advertising is cheaper than television advertising.
- Company X's sales had never risen 30 percent in a single quarter before.
- Streaming platforms reach a younger audience than television.
Reading Comprehension · inferencePassage (excerpt): "Although early economists treated consumer preferences as fixed, later research showed that the order in which options are presented measurably alters which option is chosen. This finding does not imply that preferences are random; rather, it suggests that stated preferences are constructed at the moment of choice from cues in the environment." — The passage suggests that the author would most likely agree with which statement?
- Consumer choices cannot be predicted.
- Early economists were correct that preferences are stable.
- The context in which a choice is made influences the preference that is expressed.
- Later research has been rejected by most economists.
- Randomness is the main determinant of consumer behavior.
In inference questions the correct answer is almost always the most modest one: the one you can prove from the text without adding anything.