BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Of the following intergers, which is the closest ..

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |
Legendary Member
Posts: 1448
Joined: Tue May 17, 2011 9:55 am
Location: India
Thanked: 375 times
Followed by:53 members

by Frankenstein » Tue Jun 14, 2011 9:07 pm
Hi,
Q1)(sqrt2 + sqrt5)^2 = 2+5+2sqrt(2*5) = 7+2*sqrt(10)
sqrt(10) is between 3.1 and 3.2
So, the value is between 7+2(3.1) and 7+2(3.2) i.e. 13.2 and 13.4
Hence, 3

Q2)450y= n^3 => 2*(3^2)*(5^2)y = n^3
For 2*(3^2)*(5^2)y to be a cube of integer, y should be of the form (2^2)*3*5*p^3, where p is an integer.
So, y/3x2^2x5 = p^3
We can certainly say that only I is an integer, II and III may or may not be
Hence, 2

Q3)y km/hr = y*1000 m/ (60*60)sec = 5y/18 m/sec
So, 5y/18 = x =>y =18x/5
Hence, 3
Can you check the OA for Q3.
Cheers!

Things are not what they appear to be... nor are they otherwise
Top
Master | Next Rank: 500 Posts
Posts: 401
Joined: Tue May 24, 2011 1:14 am
Thanked: 37 times
Followed by:5 members

by MBA.Aspirant » Tue Jun 14, 2011 9:10 pm
1)

(root 2+ root5)^2

2+2root10+5

7 + 2 root 10

root 10 = ~3

7 + 2*3

= 13
Top
Junior | Next Rank: 30 Posts
Posts: 22
Joined: Sun May 22, 2011 4:53 am
Thanked: 1 times
Followed by:1 members

by EddieU » Tue Jun 14, 2011 9:11 pm
if my answer is right, question 3 seemed fairly easy. the square root of 2 is 1.41 something and the square root of 5 has to be slightly higher than 2.2 maybe 2.3 since the square root of 4 is already 2. those 2 added together equals 3.6ish. since 3 squared already equals 9 and 4 squared equals 16, it has to be something in between. 10 or 13. since 3.6ish is closer to 4 I would go with 13


the 1st question, if I am not wrong, I would go with answer choice C. I'm not very sure with this one though...I made up the number 10 for x . so x=10m./s this is equal to 600m/min. (60s. in a min) this is equal to 36000m/hour. Since 1km=1000m, we have 36km/hour answer choice C offers us 18x/5. if we substitute x with 10 we have 180/5 and that equals to 36...with this one, I'm not very sure though...
Top
Master | Next Rank: 500 Posts
Posts: 401
Joined: Tue May 24, 2011 1:14 am
Thanked: 37 times
Followed by:5 members

by MBA.Aspirant » Tue Jun 14, 2011 9:20 pm
3)

X meters/1 sec = Y Km/ 1 hr

x/1 = 1000y/3600

y= 3600x/1000

y= 18x/5
Top
GMAT Instructor
Posts: 19
Joined: Mon Feb 21, 2011 7:28 am
Thanked: 6 times
Followed by:3 members

by Roy@MasterGmat » Wed Jun 15, 2011 2:04 am
Great answers by everyone.

A little addition concerning question number 3:

Since Km/h and m/s are the two most common speed units, memorizing the conversion rate between the two is a great way to avoid lengthy calculations.

10 meters per second is equivalent to 36 Km/h, meaning that 'speed in Km/h' = 3.6 * 'speed in m/s'.

In this case:

y = 3.6*x = 36/10*x = 18x/5

Or using rates:

y/x = 36/10 ---> y = 36/10*x = 18x/5
Roy
Master GMAT
Top
Junior | Next Rank: 30 Posts
Posts: 18
Joined: Wed Jun 01, 2011 11:02 pm
Followed by:1 members

by qduong » Wed Jun 15, 2011 7:36 pm
Thank you everyone for your responses. They really help me a lot.
Top
Post new topic Post Reply
• Page 1 of 1