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gamer
11-17-2006, 02:29 AM
1) a cuboid with dimensions was given(12*6*4)..and it was asked to find the volume of the smallest cube which could be formed from a "n" number of cuboids

2) An urn contains equal no of black and white balls. Randomly 3 balls are selected and wen 1 isremoved,replacement is made. wat is the prob that 2 balls selected r white ??

3)x+y+z is equal to xyz/5 ;product of x anyd y is 12.what is the value of Z n terms of Y


4)av of x , 23 and 22 is 30what is the value of x.

a) 45 b) 44.5

5)m=r^2 +s^2 + 2rs and n=r^2+s^2-2rs
what is the value of 2^m/2^n
a)1/4^rs b)1/8^rs c)1/16^rs d)32^rs e)16^rs

6) . there r three containers with capacities R S T. R contains sugar equal to 3/4th its capacity, and S contains 1/2 its capacity. if Sugar form both the containers can fill up T, T in terms of R and S would be ?

7)A(a,0) B(0,b) a is +ve,b is -ve. (a-2)^2=3 a^2b^2=25. distance AB is?

8) If the no. is 682 then
a- total no. of prime no. with 2*682
b- total prime no. with 682

9) n list "S" there are seven integers. The range of the list S is 0.
a- the avg. of nos. in list S
b- the median of nos. in list S
ans= c

10) if x=underroot(0.5)
what is the value of underroot(x)?

11) In a certain club 48 person playing football & 22 persons playing cricket and 10 are doing nothing than find person who only playing football?

12) a car is sold at s$ and he sold N cars. Person gets total P profit then what is cost price per car?
ans= (s-p/n)
how???????????


13) s={1,2,3,4,5}
t={1+t, 2+t, 3+t, 4+t, 5+t}
a- s.d of s
b- s.d of t

14) company x has 20000 employee & y has 30000 employee. In co-operation of both company total45000 employee. If one employee choose what is the probability to get that employee who is related to
both?

een
11-17-2006, 04:59 AM
Hi, gamer!
------------
Q 10
10) if x=underroot(0.5)
what is the value of underroot(x)?
If x=(0.5)^1/2, then x^1/2=((0.5)^1/2)^1/2=(0.5)^1/4
x^1/2=(0.5)^1/4
--------------
Q3
3)x+y+z is equal to xyz/5 ;product of x anyd y is 12.what is the value of Z n terms of Y
x+y+z=(xyz)/5 and xy=12, put xy=12 into equation,
so x+y+z=(12*z)/5 taking into account that x=12/y and we get
12/y+y+z=(12*z)/5
z*(12/5 -1)=y+12/y at last z=(y+(12/y))*(5/7)
-------------
Q5
5)m=r^2 +s^2 + 2rs and n=r^2+s^2-2rs
what is the value of 2^m/2^n
a)1/4^rs b)1/8^rs c)1/16^rs d)32^rs e)16^rs
The answer is e)16^rs
Consider 2^m/2^n=2^(m-n), then consider m=r^2 +s^2 + 2rs and n=r^2+s^2-2rs , m-n=r^2 +s^2 + 2rs-r^2-s^2+2rs=4rs

So 2^m/2^n=2^(m-n)=2^(4rs)=16^4s

--------------------
Q4
4)av of x , 23 and 22 is 30what is the value of x.
The answer is a) 45
We use the definition of the average
(x+23+22)/3=30, hence x=90-45=45
---------------------
Q14
14) company x has 20000 employee & y has 30000 employee. In co-operation of both company total45000 employee. If one employee choose what is the probability to get that employee who is related to
both?

To my mind,
the probability to get that employee who is related to
both equals P=a/b, here a=45000-employee in co-operation of both company
and b= 20000 +30000=50000- the total number of employee in both companies.
Hense the probability P=9/10
------
All the best!
Katya

gamer
11-17-2006, 07:04 AM
any clue abt these ones 1,2,6,7,8,9,11,12,13 thx een for ur earlier reply

een
11-17-2006, 07:43 AM
Q13
a) s.d. for s={1,2,3,4,5}
1)At first we need calculate the average value s_aver=(1+2+3+4+5)/5=3
2) For each value s_i calculate the difference between s_i and the average value s_aver , so
s_5-s_aver=5-3=2
s_4-s_aver=4-3=1
s_3-s_aver=3-3=0
s_2-s_aver=2-3=-1
s_1-s_aver=1-3=-2
2) Calculate the squares of these differences
(s_5-s_aver)^2=4
(s_4-s_aver)^2=1
(s_3-s_aver)^2=0
(s_2-s_aver)^2=1
(s_1-s_aver)^2=4
3) Find the average of the squared differences
S_a={4+1+0+1+4}/5=2
4)Take the square root of the S_a, hence s.d.=2^1/2
the standard deviation ofs s.d.=2^1/2

For s.d. of t you need to do the same procedure.

All the best!
Katya

een
11-17-2006, 09:12 AM
Gamer,
The question 11) is not clear for me enough. And can you discribe Q 6,8,9 more ? Please!
Regards,
Katya

TargetGRE6
11-17-2006, 01:42 PM
(1)
Three ways to solve this problem:
A. Find out the LCM of 12,6,4 and that would be the size of cube because sizes have to fit in. Very difficult to explain. You can leave out this approach.

B. Quickest approach - Visualize this problem if you can imagine this in your mind. You will instantly find out the solution. There is a, lets says, video cassette of 12*4*6 size. Now you rest it on side 12*6. If you place two cassettes side-by-side with side 12 as common then you will have a cuboid of size 12*12*4. Prepare two more such cuboids and place them on top of the first cuboid. Isn't the height also 12? Thus you have a cube of 12*12*12 in size. This is the aproach most suitable for GRE. Quick and a little illogical in approach.

C. A more mathematical approach
12*6*4*n=l^3
=> 2^5*3^2*n=(2*3*k)^3 -resolving both sides in prime factors and taking l=2*3*k
=> 2^2*n=3*k^3
=> 2^2*3*a=3*k^3 -assuming n=3a because prime factor 3 should be present in LHS
=> 4a=k^3
=> a=2 - For smallest prime factor.
Thus n=6 and l=12*6*4*6=12*12*12

(2) probability for white is 1/2 as urn contains equal number of black and white balls.
3 balls are selected combination for 2 balls to be white is {www,wwb,bww}
1/2*1/2*1/2 + 1/2*1/2*1/2 + 1/2*1/2*1/2
1/8+1/8+1/8 = 3/8 Ans.


(4) a. 45

(6)(3/4)R +(1/2)S=T
T=(6R+4S)/8 or (3R+2S)/4

(7) please let me know whether this expression is right (a-2)^2=3 a^2b^2=25

(8)Prime number of 682={2,11,31}
Prime number of 2*682={2,11,31}
Both have total of 3 prime numbers

(9) median and average both will be same
The range of the data set is the difference between the largest and smallest number in the set.To find the range, you simply subtract the smallest number from the largest number in the set.
Here given range is 0 o consider the list {-3,-2,-1,0,1,2,3}
here both median and average of the list is same 0


(10) x=(1/2)^(1/4)

(11) Incomplete question. Is it percentage?

(12)profit=selling price - cost price
P=sN-cp for N cars
cp=sN-p----total cost price
cp=(sN-p)/N=> s-p/N cost price per car


(13) SD is equal to both sets s and t.
http://upload.wikimedia.org/math/6/3/3/6336e4c48fd253b7a6f552fa2579525b.png

(14)45000/50000=> 9/10

please let me know the correct answer.

bscout
11-19-2006, 10:34 PM
Q13
a) s.d. for s={1,2,3,4,5}
1)At first we need calculate the average value s_aver=(1+2+3+4+5)/5=3
2) For each value s_i calculate the difference between s_i and the average value s_aver , so
s_5-s_aver=5-3=2
s_4-s_aver=4-3=1
s_3-s_aver=3-3=0
s_2-s_aver=2-3=-1
s_1-s_aver=1-3=-2
2) Calculate the squares of these differences
(s_5-s_aver)^2=4
(s_4-s_aver)^2=1
(s_3-s_aver)^2=0
(s_2-s_aver)^2=1
(s_1-s_aver)^2=4
3) Find the average of the squared differences
S_a={4+1+0+1+4}/5=2
4)Take the square root of the S_a, hence s.d.=2^1/2
the standard deviation ofs s.d.=2^1/2

For s.d. of t you need to do the same procedure.

All the best!
Katya

This question should be solved in less than five seconds: when all of the components of a set are multiplied by some number the SD is also multiplied by the same number; if a number is added or substracted to all the components of a set, the SD is the same.



(1)
Three ways to solve this problem:
A. Find out the LCM of 12,6,4 and that would be the size of cube because sizes have to fit in. Very difficult to explain. You can leave out this approach.

I'm really don't understand what the question is asking for. Anybody can try to draw a picture of it? Thanks in advance. :)

rocky80
11-20-2006, 01:54 PM
2. is it 5/24?
somehow i am not satisfied with targets answer.

TargetGRE6
11-20-2006, 03:10 PM
rocky can you explain your solution for 2nd.

rocky80
11-20-2006, 05:26 PM
probability of any ball being selected = 1/2

CASE1 . WHEN ALL THREE ARE WHITE

P = 1/8

CASE2
WHEN 2 ARE WHITE, 1 BLACK, AND THE BALL WHICH IS PUT BACK IS "BLACK"

(1/2*1/2*1/2)*2/3 = 1/12 [ 2/3 COMES FROM THE PROBABILITY
THAT THE BALL PUT BACK IS NOT WHITE]

CASE3.
1 WHITE, 2 BLACK

NOT APLLICABLE , ETC.

TOTAL PROBABILITY = 1/8 + 1/12 = 5/24 ...AM I RIGHT?

msafri
11-21-2006, 08:21 AM
q7. from given eq (note this is stated oddly, you can't have 3 ='s in one eq.)

(a-2)^2=25 --->> a-2 = +5,-5 -->> a=7,-3 ---- since a is +ve so a = 7, a^2 = 49

3*a^2*b^2 = 25 --->> b^2 = 25 / (3 * a^2) = 25/147, b= +- 25/147, b is -ve so b=-25/147


from dist formula AB = sqrt ( ( a - 0 ) ^ 2 + (0 - b) ^ 2 ) )
AB = sqrt ( 49 + 25/147)

Solving roots isn't my fav. occupation :whistle: but you get the idea

msafri
11-21-2006, 08:46 AM
@TargetGRE your q14. is wrong. The company A and B have 50000-45000 = 5000 shared employees. The total no of employees is 45000. So probability of belonging to both = 5000/45000 = 1/9

een
11-21-2006, 09:50 AM
@TargetGRE your q14. is wrong. The company A and B have 50000-45000 = 5000 shared employees. The total no of employees is 45000. So probability of belonging to both = 5000/45000 = 1/9

Hello,msafri!
IMHO, you are not right in Q14, because you need to calculate the probobility to get that employee who is related to both, so if the total number of of employee in both companies equals 50000, and in co-operation of both company 45000 employee, hense
the probability to get that employee who is related to both is 45000/50000=9/10.
May be you mean 5000/50000=1/10- the probobility to get that employee who is not related to both, then you need subtract 1/10 from 1.
Regards,
een

Pakistani
11-21-2006, 03:55 PM
Question No.2.
The four possibilities are www,wwb,wbw,bww and answer is
(1/2*1/2*1/2) +(1/2*1/2*1/2)+(1/2*1/2*1/2)+(1/2*1/2*1/2)
=1/8+1/8+1/8+1/8=4/8=1/2

Pakistani
11-21-2006, 04:01 PM
Q6. T=3/4*r+1/2*s

msafri
11-22-2006, 10:35 AM
een you are right. I thought that both companies combined had 45000 employees (mixed up the english here -- in cooperation), where as its infact 50k with 45k shared

bscout
11-22-2006, 07:52 PM
I would do this:

[2]

P(None B) = 1/8
P(One B) = 1/8
P(Three B) = 1/8
P(Two B) = 1-[P(None B)+P(One B)+P(Three B)] = 1-3/8 = 5/8

Please, anybody could clarify [1]?

hotsummertime
11-23-2006, 02:59 AM
For q 2 there is a mention of exactly 2 w balls. So the probability should be 3/8. Is not it ?

bscout
11-23-2006, 10:09 AM
Well, it is the same. Change the B by W. ;)

jahizbarlas
11-28-2006, 01:41 AM
for number 1, basically you are given one cuboid, and what you are being asked to do is arrange an n number of those same cuboids to get a cube
since you notice the biggest side is 12 of the cuboid, you should try to make a cube thats 12*12*12
Thats easy if you start with one cuboid. on whichever side you have 4, place 2 cuboids above it and you get 12 as that length. for the side 6, place on above that and you get 12 again. fill the rest of the holes to finish your cube.
hopefully that made sense. i just did it by drawing it and i suggest the same...

bscout
11-28-2006, 08:18 AM
Hence, what would be the anser for that question? By the way, anyone can do a draw of it? I still do not get it.

jinics
11-29-2006, 07:54 AM
for number 1, basically you are given one cuboid, and what you are being asked to do is arrange an n number of those same cuboids to get a cube
since you notice the biggest side is 12 of the cuboid, you should try to make a cube thats 12*12*12
Thats easy if you start with one cuboid. on whichever side you have 4, place 2 cuboids above it and you get 12 as that length. for the side 6, place on above that and you get 12 again. fill the rest of the holes to finish your cube.
hopefully that made sense. i just did it by drawing it and i suggest the same...
From tis explaination I think the answer should be n=5.
i.e. we need five more blocks of 12*6*4 to place with the already present one block of 12*6*4.i.e. a total of 6 blocks.

can somebody explain question 8,11, and 14 to me
thanx