Column A | Column B |
The units digit of 1414 | The units digit of 1616 |
Solution for GRE Math Problem 21:
The area of the circle with the radius of R is
Answer:C
The previous problem's solution is in the following post
Column A | Column B |
The units digit of 1414 | The units digit of 1616 |
Column A | Column B |
The area of the shaded region | The area of the yellow region |
Solution for GRE Math Problem 19:
Let X be Jordan's average of test scores after 5 tests. Then, he got total 5X points after 5 tests. If he gets 70 points after the next test, he'll have 5X+70 points. His average will beSolution for GRE Math Problem 18:
According to the trianglae unequation, if a triangle has sides of a and (a > =b), it is true for the third side, c, that a-b < c < a+b. Then, among the possible values for c, only (II) 11 fits the tringle unequality: 10-9 < 11 < 10+11.Solution for GRE Math Problem 17:
The amount of money, which employee earned per week is M=40x. As it left the same after the reduction of hours, the new amount of money earned per hour isSolution for Analytical Problem 3:
Let’s fix the conditions:
The West Field must be planted with either barley or beans:
W: Ba OR Be
At least one field must be planted with corn.
Co: N OR E OR S
If, in the previous year, a field was planted with beans, then it must be planted with beans again.
Be –> Be
If, in the previous year, a field was planted with either wheat or alfalfa, then it must be planted with oats.
Wh –> Oa
Al –> Oa
To answer Question I we should first use condition 1 to cross out answer A (oats of the field for beans or barney). Then, we can see, that answers B and C have no place for corn. Then, in answer E one filed is planned for Alfalfa, which is not mentioned among four crops for this yesr. So, the answer is D.
Answer: D oats, barley, corn, beans.
To solve Question II, let’s draw a table:
| N | E | S | W |
Year 1 |
| Wh | Be |
|
Year 2 |
|
|
|
|
We can determine the crops for Year 2 in E and S:
| N | E | S | W |
Year 1 |
| Wh | Be |
|
Year 2 |
| Oa | Be |
|
The only place for corn left in the Year 2 is the North field, so, answer B must be true.
Answer: B The North Field is planted with corn.
Among the answers Question III we must look for one, which violates conditions for Western field. And we can see that if the Western field had been planted with alfalfa, then we’d have to plant neither barney, nor beans, but only wheat there the following year.
Answer: A alfalfa.
We’ll need a table again to arrange data from Question IV:
| N | E | S | W |
Year 1 | Oa | Oa | Oa | Co |
Year 2 |
|
|
|
|
So, the crop in the Western must be changed. Besides, the crop in one of the other fields must be changed to corn. That’s why no less that two fields must be planted with crops that are different from those planted there for the previous year.
Answer: C two.
In Question V we should remember about the field for corn. The following year three fields will be planted with beans and the forth one – with corn. But the fourth one can’t be the Western field, because the Western field will be planted with beans or barney. The fourth field can’t be planted neither with wheat or beans, because it will be planted either with oats, or with beans the following year. So, we can see, that the fourth field was planted with oats.
Answer: C the fourth field was planted with oats.
Question VI can be solved with the help of the table:
| N | E | S | W |
Year 1 | Oa | Be | Al |
|
Year 2 |
|
|
|
|
Using the initial conditions. We can determine the crops for Year 2:
| N | E | S | W |
Year 1 | Oa | Be | Al |
|
Year 2 | Co | Be | Oa | Ba OR Be |
Answer: A Corn is planted in the North Field.
A farm is divided into four fields designated as the North Field, the East Field, the South Field, and the West Field. For the new growing season, each of the fields will be planted with exactly one of four crops—corn, beans, barley, or oats— according to the following plan:
Question I. Which of the following could be the crops planted?
| North | East | South | West |
A | beans | corn | barley | oats |
B | beans | barley | oats | beans |
C | wheat | barley | oats | beans |
D | oats | barley | corn | beans |
E | alfalfa | corn | beans | beans |
Question II. If, in one year, the East Field is planted with wheat and the South Field is planted with beans, which of the following must be true of the year immediately following?
(A) The North Field is planted with barley.
(B) The North Field is planted with corn.
(C) The West Field is planted with barley.
(D) The South Field is planted with oats.
(E) The East Field is planted with beans.
Question III. In the previous growing season, the West Field could have been planted with any of the following crops EXCEPT
(A) alfalfa
(B) beans
(C) barley
(D)oats
(E) corn
Question IV. If, in the previous growing season, the West Field was planted with corn and the other three fields were planted with oats, what is the minimum number of fields that must be planted with crops that are different from those planted there for the previous growing season?
(A) None
(B) One
(C) Two
(D) Three
(E) Four
Question V. If three of the four fields were planted with beans for the previous growing season, which of the following could also have been true of the previous growing season?
(A) Barley was planted in the West Field.
(B) Corn was planted in the West Field.
(C) The fourth field was planted with oats.
(D) The fourth field was planted with wheat.
(E) The fourth field was planted with beans.
Question VI. If, for the previous growing season, the North Field was planted with oats, the East Field was planted with beans, and the South Field was planted with alfalfa, which of the following must be true of the new growing season?
(A) Corn is planted in the North Field.
(B) Oats are planted in the North Field.
(C) Barley is planted in the East Field.
(D) Barley is planted in the West Field.
(E) Beans are planted in the West Field.
Solution for GRE Math Problem 16:
This problem doesn't need much calculation. Knowing that 2468=2000+400+60+8=2x3+4x102+6x10++8 we can say that the columns are equalCompare two values:
Column A | Column B |
2468 | 8+6x10+4x102+2x103 |
Solution for GRE Math Problem 15:
If b books can be purchased for d dollars, thenSolution for GRE Math Problem 14:
By opening the brackets we get x+y+7 in Column A, which is bigger than x+y-7 in Column B.Compare two values:
Column A | Column B |
x+y-7 |
Solution for GRE Math Problem 13:
Let's use formula for the squares of sum and difference:Compare two values:
Column A | Column B |
(a+b)2 | (a-b)2 |
Solution for GRE Math Problem 12:
The sum of those two angles of quadrilateral is 2x60=120o. Since the sum of all four angles of quadrilateral is 360o, the sum of other two angles is 360-120=240o and their average is 240/2=120. So, the columns are equal.Compare two values:
Column A | Column B |
The average of the measures of the other two angles | 120° |
Solution for GRE Math Problem 11:
Average of x and y lies exactly in the middle between x and y. Average of x, y and y lies between x and y, but closer to y. As y is bigger than x, columb B is greater.Column A | Column B |
The average (arithmetic mean) of x and y | The average (arithmetic mean) of x, y, and y |
Solution for GRE Math Problem 10:
In 1990 for twice less money we could buy twice more potatoes. So, the cost became 2x2=4 times less than in 1980. So, the price in 1990 was a quarter or 25% of the price in 1980. But the question is “By what percent did the price of potatoes decrease from 1980 to 1990?” Assuming price in 1980 as 100%, we get 100%–25%=75%Solution for GRE Analytical Problem 2:
We’ll name countries for their first letters: B, C, D, E, F, G. Now we shall make some preliminary conclusion from the conditions.
Having 6 films and 4 days, we’ve got a math problem here:
In how many ways can we get 6 out of 4 positive integers, with any two consecutive terms not bigger than 3?
If the first number is 2, then the second must be 1. The third and the forth numbers can be 1+2 or 2+1.
So, we have two ways for now: 2+1+1+2 and 2+1+2+1.
And if the first number is 1, the second number can’t 1 (otherwise the sum of the third and the fourths numbers would be 4). So, only one possibility is there: 1+2+1+2
Now we have three possible patterns for showing films during the festival:
1+2+1+2
2+1+1+2
2+1+2+1
They’ll be useful during our further solution
It’s time to start filling the table:
Thu | Fri |
Sat |
Sun |
|
|
B |
|
C+X
F – G
E – D
IMPORTANT Note: phrase “on a day after” shows that any number of days can pass between English and Danish films. To indicate two consecutive days phrases like “on a day immediately after”, “on a next day” etc.
And one more to do in the preparatory phase is to make a restriction table:
Thu | Fri |
Sat |
Sun |
|
|
|
|
Now we may proceed to answering questions.
Question I
B cant’ be shown on Thu, for it has already been scheduled to Sat. C must be accompanied by another film, so, it can’t be shown on Thu, either. D and G are in our restriction table for Thu. So, only F remaining.
Answer (D) France
Question II
If F is on Sat, the G is on Sun. The only pattern with 2 films on Sat is 2+1+2+1, so, C must be on Thu, so must E. And Ð’ will be shown on Fri
Thu | Fri |
Sat |
Sun |
C |
D |
B |
G |
Now we can see, that (B) The film from Denmark will be shown on Friday is the only possible answer.
Answer (B)
Question III
With two films on Thu and two on Sun, we have 2+1+1+2 pattern. So, C can’t be shown on Fri. Neither does B, because it is shown on Sat. And any of other four films may be shown on Friday.
D:
Thu | Fri |
Sat |
Sun |
E |
D |
B |
G |
E:
Thu | Fri |
Sat |
Sun |
F |
E |
B |
D |
F:
Thu | Fri |
Sat |
Sun |
E |
F |
B |
D |
G:
Thu | Fri |
Sat |
Sun |
F |
G |
B |
D |
Answer (D) 4
Question IV
If the English and German films are shown on the same day, we have
F – E+G –D
Thus, E+G can’t be shown neither on Thu, nor on Sun. These films can’t be shown on Sat, because in that case we would have three films then. So, E+G must be on Fri and we have 1+2+1+2 pattern.
Thu |
Fri |
Sat |
Sun |
|
E |
B |
|
F must be on Thu, D and C – on Sun
Thu | Fri |
Sat |
Sun |
F |
E |
B |
C |
That’s why answer (E) “he film from Canada will be shown on Sunday” is the only true possibility.
Answer (E)
Question V
If the film from England is shown on Saturday, we have 2+1+2+1 pattern.
Thu | Fri |
Sat |
Sun |
|
|
B |
|
Sunday slot must be taken by D.
Thu | Fri |
Sat |
Sun |
|
|
B |
D |
C must be shown on Thursday:
Thu | Fri |
Sat |
Sun |
C |
|
B |
D |
At last, F and G will take Thu and Fri slots.
Thu | Fri |
Sat |
Sun |
C |
G |
B |
D |
Now we can see, that the film from Germany cannot be shown on the same day as any other film.
Answer (E) The film from Germany.
The Fairfield Foreign Film Festival plans to show six films—one each from Belgium, Canada, Denmark, England, France, and Germany. The festival will open on a Thursday and close three days later on a Sunday. Each film will be shown once during the four days of the festival.
The order in which the films will be shown must adhere to the following conditions:
Question I
If only one film is shown on Thursday, it could be the entry from which of the following countries?
(A) Belgium
(B) Canada
(C) Denmark
(D) France
(E) Germany
Question II
If the Belgian and French films are shown on the same day, which of the following must be true?
(A) The film from Denmark will be shown on
Thursday.
(B) The film from Denmark will be shown on
Friday.
(C) The film from Germany will be shown on
Thursday.
(D) The film from Canada will be shown on
Sunday.
(E) The film from England will be shown on
Sunday.
Question III
If the director of the festival decides to show two films on Thursday and two on Sunday, how many films would be eligible to be shown on Friday?
(A) 1 (B) 2 (C) 3 (D) 4 (E) 5
Question IV
If the English and German films are shown on the same day, which of the following must be true?
(A) The film from England will be shown on
Thursday.
(B) The film from France will be shown on Friday.
(C) The film from Canada will be shown on
Saturday.
(D) The film from Germany will be shown on
Saturday.
(E) The film from Canada will be shown on
Sunday.
Question V
If the film from England is shown on Saturday, which of the following films cannot be shown on the same day as any other film?
(A) The film from Belgium.
(B) The film from Canada.
(C) The film from England.
(D) The film from France.
(E) The film from Germany.
Solution for GRE Math Problem 9:
Solution for GRE Math Problem 8:
Total steps down: 4+6+2=12Solution for GRE Math Problem 7:
Solution for GRE Math Problem 6:
Solution for GRE Math Problem 5:
Column A | Column B |
3 times the number of floors in the building | The number of apartments in the building |
Let’s name the patients B, C, D, E, F, G for their first letters. L will be used for lunch.
Let’s draw a table for sessions and fill it with known information:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
|
|
L |
F |
|
|
Then we’ll make some notes to fix other pieces of information:
D – E
B – E
B – F
CG
What preliminary conclusion cam we make of this?
Restrictions 2-5 can be shown graphically:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
|
|
|
|
|
|
Now, we can proceed to Question I.
“Bernstein is only available at 10:00” means, that B will in the second slot
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
B |
|
L |
F |
|
|
Now, looking at the table, we can see only one pair of adjacent sessions for CG: at 2:00 and 3:00
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
B |
|
L |
F |
C |
G |
Then, as E can take the session at 9:00, he’ll take 11:00 session:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
B |
E |
L |
F |
C |
G |
And the session at 9:00 is for D
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
D |
B |
E |
L |
F |
C |
G |
So, we have only one way to schedule sessions if B is on 10:00.
Answer A
Note: we have not to check if D at 9:00 fits the requirements, because there isn’t 0 among possible answers. Otherwise, to judge between 0 and 1 we’d had to prove that D at 9:00 doesn’t violate any requirement.
Question II alters initial data:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
|
|
L |
C |
|
|
Having place for C, we can see he place for G:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
|
|
L |
C |
G |
|
Session at 3:00 can’t be taken by F (because he switched to the morning), by B or by D. That’s why the last session must be taken by E.
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
|
|
L |
C |
G |
E |
Since F can’t be the first, we have two possibilities for him:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
F |
|
L |
C |
G |
E |
|
|
F |
Then, we’ll place B before F
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
B |
F |
|
L |
C |
G |
E |
B |
|
F |
||||
|
B |
And in every arrangement the place for D is clearly determined
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
B |
F |
D |
L |
C |
G |
E |
B |
D |
F |
||||
D |
B |
Now we can see that in every case Dawson or Friedman has the third session of the day.
Answer D
We shall start solving Question III from our initial table with G added to 3:00 slot
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
|
|
L |
F |
|
G |
The place for C is determined:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
|
|
L |
F |
C |
G |
Now, looking to restriction table we find place for E:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
|
|
E |
L |
F |
C |
G |
And we have two variants for B and D
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
B |
D |
E |
L |
F |
C |
G |
D |
B |
Now we can see, that answer “(D) Edson has her session at 10:00” can’t be true;
Answer: D
Note: We could find this answer merely by looking at our restriction table, thus, saving precious time.
In Question IV there are two places for C (and for G, then):
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
C |
G |
|
L |
F |
|
|
|
C |
G |
Then, place for B is determined:
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
C |
G |
B |
L |
F |
|
|
B |
C |
G |
Now we can see, that possibilities (A)-(D) are not necessary true. Then, correct answer if “(E) Dawson has a session at 2:00”. Really, as 3:00 slot is restricted for D, he can be placed only to 2:00 slot, and 3:00 session must be for E
9:00 |
10:00 |
11:00 |
12:00 |
1:00 |
2:00 |
3:00 |
C |
G |
B |
L |
F |
D |
E |
B |
C |
G |
Answer: E
n is an odd positive integer
Compare two values:
Column A | Column B |
The number of prime factors of n | The number of prime factors of 2n |
Solution for GRE Math Problem 3:
Lets consider three possibilities: numbers x and y can be bot positive, negative and positive and 0 and 1. (They both can't be negative, because their sum is x+y=1>0).Compare two values:
Column A | Column B |
xy | 1 |
Solution for GRE Math Problem 2:
Column A | Column B |
65% of a |
Column A | Column B |
The sum of the positive divisors of 19 | The product of the positive divisors of 19 |