GMAT Prep problems couple of questions

This topic has expert replies
Newbie | Next Rank: 10 Posts
Posts: 7
Joined: Tue Oct 27, 2009 1:54 am

GMAT Prep problems couple of questions

by jpnguyen » Wed Feb 24, 2010 3:30 pm
Alright, well just took GMAT Prep 1 after 3 months of studying and scored a 680 47Q 36V. I'm happy with the diagnostic score and I plan to take about 10 more tests in the next month before my real GMAT exam. I made a bunch of careless mistakes in quant but I seriously don't get a few of these. In particular 3,4,5. And I just want clarification for methods used on 1,2. 2: I suppose is zero because 2,2,5 cannot equal a triangle since 2+2<5.

1. In the arithmetic Sequence t1, t2, t3,...,tn,..., t1=23 and tn=tn-1 -3 for each n>1. What is the value of n when tn=-4?
A. -1
B. 7
C. 10
D. 14
E. 20

OA: C

2. If two sides of a triangle have lengths 2 and 5, which of the following could be the perimeter of triangle?
I. 9
II. 15
III. 19
A. None
B. I only
C. II only
D. II and III only
E. I, II, and III

OA: A



3. See attachment
OA: C


4. A thin piece of wire 40 meters long is cut into two pieces. One piece is used to form a circle with radius r, and the other is used to form a square. No wire is left over. Which of the following represents the total area, in square meters, of the circular and the square regions in terms of r?
A. (Pi)r^2
B. (Pi)r^2 + 10
C. (Pi)r^2 + (1/4)*(Pi)^2*(r^2)
D. (Pi)r^2 + (40 -2(Pi)r)^2
E. (Pi)r^2 + [10 - (1/2)*(Pi)*r]^2

OA: E

5. The sequence a1, a2, a3,...,a(n) of n integers is such that a(k)=k if k is odd and ak=-a(k-1) if k is even. Is the sum of the terms in the sequence positive?
(1) n is odd
(2) a(n) is positive

OA: D

Image
Source: — Problem Solving |

User avatar
Community Manager
Posts: 1537
Joined: Mon Aug 10, 2009 6:10 pm
Thanked: 653 times
Followed by:252 members

by papgust » Wed Feb 24, 2010 9:55 pm
Hi jpguyen,

Firstly, if you are not aware of the forum rules, please find time to go through them. You should do a search for the question you are looking for, before you post. For this time, i will help you out in searching the questions. Here are the links,

https://www.beatthegmat.com/gmat-prep-th ... 10448.html
https://www.beatthegmat.com/triangles-t24497.html
https://www.beatthegmat.com/tough-sequen ... ent=Boston
https://www.beatthegmat.com/gmat-prep-ar ... t8798.html

For the 3 rd question, the image is not visible to me as my network blocks the images. Please do a search for the 3rd qn by yourself. You should only post when there is any specific doubt or when you have difficulty with the existing solutions in the forum.

Also, don't forget to use the spoiler to hide your answers. This will help other people to solve the problem without looking at the answer.

Legendary Member
Posts: 610
Joined: Fri Jan 15, 2010 12:33 am
Thanked: 47 times
Followed by:2 members

by kstv » Wed Feb 24, 2010 10:50 pm
Though I can see the picture I cannot label it.
So if you can follow the notations.

1) If QR = RS , angle RQS = RSQ = a° , not sufficient.

2) ST = TU , angle TSU = TUS = b°, not sufficient.

We know angle PRT = c° and PTR = d° is = 90°

take angle QST = x°+b°= a°+c°
similarly USR = x°+a° = b° + d°
add both and you get 2x°= c°+d°

Hence C, but in DS it is not necessary to solve the eq.

Senior | Next Rank: 100 Posts
Posts: 87
Joined: Wed Jan 06, 2010 8:16 pm
Location: Chandigarh, INDIA

by onedayi'll » Thu Feb 25, 2010 8:22 am
Question 4:


2.pi.r+4s(side of the sqare) = 40
s=40-2.pi.r)/4==> (10-.5pi.r)^2

Therefore
Total area = Area of the circle (pi.r^2)+(10-.5pi.)^2 ==> E

Many of us will make a mistake that 20 is the radius, but rather its the circumference of the circle.
So r = 10/Pi.
Gym/GMAT/Girl -- Be Serious