●Question 1. Sentence Correction

Direction: Correct the underlined part

Often visible as smog, ozone is formed in the atmosphere from hydrocarbons and nitrogen oxides, two major pollutants emitted by automobiles, react with sunlight.

A. ozone is formed in the atmosphere from
B. ozone is formed in the atmosphere when
C. ozone is formed in the atmosphere, and when
D. ozone, formed in the atmosphere when
E. ozone, formed in the atmosphere from

●Question 2. Critical Reasoning

Escalating worldwide demand for corn has led to a sharp increase in the market price of corn, and corn prices are likely to remain high. Corn is extensively used as feed for livestock, and because profit margins are tight in the livestock business, many farmers are expected to leave the business. With fewer suppliers, meat prices will surely rise. Nonetheless, observers expect an immediate short-term decrease in meat prices.

Which of the following, if true, most helps to justify the observers’ expectation?

A. The increase in corn prices is due more to a decline in the supply of corn than to a growth in demand for it.
B. Generally, farmers who are squeezed out of the livestock business send their livestock to market much earlier than they otherwise would.
C. Some people who ate meat regularly in the past are converting to diets that include little or no meat.
D. As meat prices rise, the number of livestock producers is likely to rise again.
E. Livestock producers who stay in the business will start using feed other than corn more extensively than they did in the past.

●Question 3. Data Sufficiency

Directions: In this problem, a question is followed by two statements containing certain data. You are to determine whether the data provided by the statements are sufficient to answer the question.

Is the average (arithmetic mean) of 5 different positive integers at least 30?

Condition 1) each of the integers is a multiple of 10
Condition 2) the sum of the 5 integers is 160

A. statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question
B. statement 2 alone is sufficient, but statement 1 alone is not sufficient to answer the question
C. both statements taken together are sufficient to answer the question, but neither statement alone is sufficient
D. each statement alone is sufficient
E. statements 1 and 2 together are not sufficient, and additional data is needed to answer the question

●Question 4. Problem Solving

Three boxes of supplies have an average (arithmetic mean) weight of 7 kilograms and a median weight of 9 kilograms. What is the maximum possible weight, in kilograms, of the lightest box?
A. 3kg B. 4kg C. 5kg D. 6kg E. 7kg



———————————————————————

●Answer to Q1: B
Because the preposition ‘from’ can’t be followed by a clause, ‘from’ in A and E should be replaced with a subordinate conjunction. Also, D and E are causing the sentence fragment since there is no verb in each answer choice. In C, the conjunction ‘and’ should be omitted in that a ‘when-clause’ needs no coordinate conjunction in modifying the preceding main clause.

●Answer to Q2: B
The conclusion of this argument is that observers expect an immediate short-term decrease in meat prices despite meat prices being likely to rise following higher corn prices. The question is asking for an answer choice that justifies this conclusion. Choice A explains why corn prices are rising, which is given as a premise in the argument. Choice B tells us that as farmers cannot afford rising corn prices, they are forced to sell their livestock earlier which will cause increase in meat supply. More supply can cause the meat prices to fall in short-term, thus choice B is the correct answer. Choice C implies that demand for meat is in decline which could cause meat prices to fall. But this choice exceeds the boundary set by the conclusion that the price decline will be short-term. Identifying boundaries is the key to finding a right choice in GMAT problems. Choices D and E will mitigate the upward pressure and help meat prices stabilize.

●Answer to Q3: D
Condition 1) 10+20+30+40+50=150, is sufficient since those are the smallest numbers of the different positive integers.
Condition 2) Since the average (arithmetic mean) is the sum is divided by the number of the set, the average (arithmetic mean) is 160/5=32>30, is sufficient, therefore the best answer is D.

●Answer to Q4: A
x+9+y=7*3=21(x<=9<=y), because x is the max weight, y is the smallest weight, x+9+9=21, x=3, therefore the best answer is A.

STN Academy helps students prepare for the GMAT (Graduate Management Admission Test), which is required by most business schools in the world. It is located near Gangnam Station in southern Seoul. Visit www.stnacademy.com or call 02-501-4801 for more information.