GMAT Exercise 16

Question 1: Sentence Correction

Scorched by fire, stained by water, and inscribed in cramped handwriting, the seventeenth-century Dutch documents on the beginnings of New York City were long ignored by historians, depending instead on English sources for information.

(a) the seventeenth-century Dutch documents on the beginnings of New York City were long ignored by historians, depending

(b) the seventeenth-century Dutch documents on the beginnings of New York City were long ignored by historians, who depended

(c) historians long ignored the seventeenth-century Dutch documents on the beginnings of New York City, depending

(d) historians long ignored the seventeenth-century Dutch documents on the beginnings of New York City and depended

(e) historians long ignored the seventeenth-century Dutch documents on the beginnings of New York City, they depended

Questio 2: Critical Reasoning

Two groups of laboratory mice were injected with cancerous cells. One group’s cages were rotated in a disorienting manner. Two-thirds of these mice developed cancers. One-tenth of the mice in stationary cages developed cancers. The researchers concluded that stress enhances the development of cancer in laboratory mice.

The researchers’ conclusion logically depends on which of the following assumptions?

(a) Rotating the cages in a disorienting manner produced stress in the mice in those cages.

(b) The injections given to the two groups of mice were not of equal strength.

(c) Injecting the mice with cancerous cells caused stress in the mice.

(d) Even without the injections the mice in the rotated cages would have developed cancers.

(e) Even the rotation of cages in a manner that is not disorienting is likely to produce stress in mice in those cages.

Question 3: Data Sufficiency

If x and y are positive integers, is x^4 -y^4 divisible by 3?

1) x-y is divisible by 3.

2) x+y is divisible by 3.

Question 4: Problem Solving

Which of the following is the closest to 10^(-5)-10^(-12)?

A. 10^(-5) B. 10^(-6) C. 10^(-8) D. 10^(-10) E. 10^(-12)

Answer to Q1 : B

The preceding participle phrase ‘scorched by fire, stained by water, and inscribed in cramped handwriting’ needs ‘the seventeenth-century Dutch documents’ as the subject of the whole sentence in terms of the logical meaning. And the relative clause ‘who depended instead on English sources for information’ in B is more effective in modifying ‘historians’ than the participle phrase ‘depending instead on English sources for information’ in A. So, the answer is B.

Answer to Q2 : A

The statement concluded with the rate of mice in different cages that stress enhances the development of cancer in laboratory mice. This conclusion is depending upon the assumption that rotating the cages in a disorienting manner produced stress in the mice in those cages. Otherwise, the researchers can’t assert the connection between stress and the development of cancer in laboratory mice. The answer choice of A is the only one that is mentioning the relation directly. Therefore, the answer is A.

Answer to Q3

Because (x^4-y^4)=(x-y)(x+y)(x^2-y^2), 1) x-y=3t(t:integer), sufficient, 2) x+y=3s(s:integer) ,sufficient, therefore the best answer is D.

Answer to Q4

Because 10^(-12) is almost zero, 10^(-5)-10^(-12) is closer to 10^(-5), therefore the best answer is A.