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Multiple questions please help

by torofish » Sat Jan 02, 2010 11:23 am
There are no answers for these questions. What are your answers.

1.) K is a multiple of 11. Is KL a multiple of 154?
1.) L has all the same factor as 42.
2.) K is divisible by 21.
Couldn't do.


2.) What's the ratio of X to Y?
1.) .8X+.5Y=40
2.) .625Y=50-X

My Answer: E


3.) There are 50 marbles: Red, White, Black. How many is Red?
25 are not Black. 40 are not White.
15 more Black than White. 5 more Red than White.

25 are not black means 1.) R+W=25 or it's not necessary be like that. I solved by assuming that R+W = 25 and R+B = 40

My Answer: D


4.) If X is an integer. Is 2^x a factor of 12!?
X is the sum of two distinct single-digit prime.
0<X<11

My answer: D


5.) Are V and W integers?
√v+w=integer <-- v+w is under square root
v/w=integer

My answer: C
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by raviraushanjha » Sat Jan 02, 2010 7:34 pm
1.) K is a multiple of 11. Is KL a multiple of 154?
1.) L has all the same factor as 42.
2.) K is divisible by 21.

Form 1 :
Prime Factors of 42 = 2, 3,7
Prime Factors of K (least multiple of 11) = 11
So the minimum factors of KL = 2, 3, 7, 11
Factors of 154 = 2,7,11
Hence Sufficient.

From 2: K is divisible by 21. Thus factors of k will include : 3,7
but for KL to be divisible we need a prime factor 2 in L which is not mentioned.
Insufficient.

IMO : Ancwer A
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by raviraushanjha » Sat Jan 02, 2010 7:41 pm
2.) What's the ratio of X to Y?
1.) .8X+.5Y=40
2.) .625Y=50-X

Two equations two unknowns. IMO Answer : C
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by raviraushanjha » Sat Jan 02, 2010 7:50 pm
3.) There are 50 marbles: Red, White, Black. How many is Red?
1) 25 are not Black. 40 are not White.
2) 15 more Black than White. 5 more Red than White.

From 1

Black = 50-25 = 25
Whilte = 50-40 = 10
Red +Black+White = 50
Red = 15
Sufficient

From 2

B = W+15
R = W+ 5
R+ B+W = 50

three unknowns 3 quation. Sufficient
IMO : Answer D
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by raviraushanjha » Sat Jan 02, 2010 7:59 pm
4.) If X is an integer. Is 2^x a factor of 12!?
X is the sum of two distinct single-digit prime.
0<X<11

12! = 1*2*3*4*5*6*7*8*9*10*11*12

= 1*2*3*2*2*5*2*3*7*2*2*2*9*2*5*11*2*2*3

=(2^10) * 3*5*3*7*9*5*11*3

From 1:

x can be 7+5 = 12 thus not a factor of 12!

insufficient

From 2

0<x< 11 any value of x from 1-10 will make it a factor... sufficient.

IMO : Answer : B
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by ramsharma » Sun Jan 03, 2010 2:22 am
Check again,Even if there are two equations there is no solution.
ax+by=c
dx+ey=f

if a/d=b/e,then there will be no solution

IMO:E

======================
2.) What’s the ratio of X to Y?
1.) .8X+.5Y=40
2.) .625Y=50-X

Two equations two unknowns. IMO Answer : C

====================================

5.) Are V and W integers?
√v+w=integer <-- v+w is under square root
v/w=integer

My answer: C


IMO should be E
stat 1:if v=1/2,w=1/2 then sqrt(v+w):1 which is a integer,but v w non integer
if v=2,w=2,then then sqrt(v+w):1 which is a integer and v,w integer

insuff

stat 2:same for statement 2 same value of v and w will satisfy
insuff

stat 1 and stat 2; same value of v and w will satisfy

hence insuff


Ram
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by mehravikas » Mon Jan 04, 2010 4:30 pm
Please use spoilers even if the answers are IMO's
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