How to ace the GMAT in 28 days: Day 20 (analysing 740)

Ok, time to analyse my errors in that 740. 108 questions, giving me corrected raws of 51V/42Q.


A flat triangular cornfield has the dimensions shown in the figure above. If y^2 = 2, what is the area of the field in square miles?

(A) 1/4
(B) √3 / 4
(C) 1/2
(D) √3 / 2
(E) 1

I chose C. Under the right-angle-triangle rule, the square of the hypotenuse is equal to the sum of the squares of the other two sides, so the length of the base is √2^2 – (√2/2)^2, which is 2 – 1/2. The square of the base is 1.5. The area of a triangle is half the base times the height, so √1.5 * 1.5 * y/2. 1.5√2/2, which is 0.75√2/2, which is √3/4. The answer is B.

A Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D EACH Statement ALONE is sufficient.
E Statements (1) and (2) TOGETHER are NOT sufficient.

Does nm =40?
(1) 10/n = m/4
(2) 5n = 20 and 8m = 80

I chose B. But of course, 10/n and m=4 gives the answer, as does statement 2. It’s D.

Is the value of x^2 + xy equal to 0?

(1) x = 0
(2) y = 0

I chose D, falling into the trap. It’s okay for x to equal 0, since that would make both x^2 and xy equal to 0, giving us enough info to answer the question. But y=0 would let x be any number we like, and the answer wouldn’t be 0. It’s A.

If a + b= 200 and a c + d?
(1) c + d < 200
(2) b + c + d = 300

I chose A, since obviously statement 1 is enough; a+b = 200 and c+d < 200 makes it easy. But Statement 2 works as well, since b must be at least 1 more than a, or 101 if a+b=200 is to hold. So c+d can't be more than 199, giving us enough info again. It's D.

Between 3:00 am. and 3:00 p.m. of the same day, the minute hand of a properly operating clock, indicated by the figure above, will turn through how many degrees?

(A) 0
(B) 1,200
(C) 2,160
(D) 4,320
(E) 8,640

I guessed E. This question foxed me. Between 3am and 3pm are 12 hours; the minute hand goes around 60 x 12 times, which is 720; there are 360 degrees in a circle, so the minute hand has traversed the 360 degrees 720 times. Which is a lot more than any of the options.

The question is ‘wrong’ due to an inconsistency in English usage: many people would call the minute hand the ‘hour hand’. The hand that marks off the hours turns 12 times, 12 times 360, which is D. With a moment’s thought I’d have seen my mistake.

If n is a positive integer, the sum of the integers from 1 to n, inclusive, equals n(n+1) / 2. Which of the following equals the sum of the integers from 1 to 2n, inclusive?

(A) n(n+1)
(B) n(2n+1) / 2
(C) n(2n+1)
(D) 2n(n+1)
(E) 2n (2n+1)

Was all at sea with this one, choosing B. The clue is in the 2: you’ve got to double the n(n+1)/2, giving n(n+1), but since it’s a range you’ve got to separately double the extent of the range, which is the n in brackets. It’s C.

If x is the average (arithmetic mean) of 5 consecutive even integers, which of the following must be true?

I. x is an even integer.
II. x is a nonzero integer.
III. x is a multiple of 5.

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

I (stupidly) chose E. But of course II can’t be right: it doesn’t have to be nonzero, or even an integer; the numbers could be -4, -2, 0, 2, 4. Following on, III can’t be right either, since zero isn’t divisible by 5. Only I can hold, and if all the terms are even, the average must be even too. It’s A.


A United States manufacturer of farm equipment reported a 1988 third-quarter net income of $32 million, compared with $25.5 million in the third quarter of 1987. This increase was realized despite a drop in United States retail sales of farm equipment toward the end of the third quarter of 1988 as a result of a drought.

Which of the following, if true, would contribute most to an explanation of the increase in the manufacturer’s net income?

(A) During the third quarter of 1988, the manufacturer announced that it would add irrigation systems to its line of products.
(B) In the third quarter of 1988, the manufacturer paid no wages during a six-week strike, but stocks on hand were adequate to supply dealers.
(C) Sales in the United States of farm equipment made and sold by foreign companies were higher in the third quarter of 1988 than in any previous quarter.
(D) Official dealers of the manufacturer had low supplies of farm equipment during the third quarter of 1988.
(E) Eligible United States farmers benefited from a federal drought-relief fund late in the third quarter of 1988.

I chose D. This is an inference question, among the hardest. The clue is in ‘net revenues’; if sales dropped, something happened to take some costs out of the equation. The only answer that reduces costs (hence increasing net revenues) is B.

During the nineteenth century, occupational information about women that was provided by the United States census—a population count conducted each decade— became more detailed and precise in response to social changes. Through 1840, simple enumeration by household mirrored a home-based agricultural economy and hierarchical social order: the head of the household (presumed male or absent) was specified by name, whereas other household members were only indicated by the total number of persons counted in various categories, including occupational categories. Like farms, most enterprises were family run, so that the census measured economic activity as an attribute of the entire household, rather than of individuals.
The 1850 census, partly responding to antislavery and women’s rights movements, initiated the collection of specific information about each individual in a household. Not until 1870 was occupational information analyzed by gender: the census superintendent reported 1.8 million women employed outside the home in “gainful and reputable occupations.” In addition, he arbitrarily attributed to each family one woman “keeping house.” Overlap between the two groups was not calculated until 1890, when the rapid entry of women into the paid labor force and social issues arising from industrialization were causing women’s advocates and women statisticians to press for more thorough and accurate accounting of women’s occupations and wages.

It can be inferred from the passage that the 1840 United States census provided a count of which of the following?

(A) Women who worked exclusively in the home
(B) People engaged in nonfarming occupations
(C) People engaged in social movements
(D) Women engaged in family-run enterprises
(E) Men engaged in agriculture

I chose E, since it’s the only one stated explicitly (the census counted male heads of household, and differentiated farmers from other workers.) But that doesn’t go far enough: it counted all workers engaged in agriculture, but didn’t define them as male if they weren’t heads of households. The other answers fail on the same criterion. It’s B.

Contrary to the scholarly wisdom of the 1950’s and early 1960’s that predicted the processes of modernization and rationalization would gradually undermine it, ethnicity is a worldwide phenomenon of increasing importance.

(A) would gradually undermine it
(B) to be a gradual undermining of it
(C) would be a gradual undermining of ethnicity
(D) to gradually undermine ethnicity
(E) gradually undermining it

Another of those ‘standard grammar’ questions, which as a copywriter (we write the way people speak) I’m surprisingly poor at. I chose E, but the only one that fits the sense correctly is A.

Tektites, which may have been propelled to Earth from lunar volcanoes, are much like the volcanic glass obsidian, but their chemical composition is different than any terrestrial lava; they contain far less water than obsidian does and none of its characteristic microcrystals.

(A) is different than any terrestrial lava; they contain
(B) is different than any terrestrial lava’s, containing
(C) is different from that of any terrestrial lava; they contain
(D) differs from any terrestrial lava in containing
(E) differs from that of any terrestrial lava’s, containing

I chose E. A and B are out, since the ‘than any’ makes the comparison between the composition and the lava, not the composition of the tektites and the composition of lava. D and E work grammatically but fall down later on with the obsidian ‘does’. It’s C.

Hmmm… a few silly mistakes, meaning that if I stay sharp on test day I’m on course for 750. A week of practice beckons; time to take it up a notch.

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