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bagrettin
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no.prop 06 Jul 2011, 00:32
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A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

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50% (02:04) correct 50% (02:22) wrong based on 4 sessions

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I think we could just eliminate each statement by a contr-example here.
Take x=6, y=9. You have 3*6/9=2 which is a prime number.

x is not y, y is not 1, x is not a prime number. So neither statement must be true, therefore the answer is A.



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rohanrodrigues
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no.prop 06 Jul 2011, 11:00
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Can someone help me out on this?

if x=y, 3x/y = 3 which is prime number so statement 1 can be true
y=1, 3x will not be a prime number, Statement 2 false
for statement 3, if x=11 and y=13, 3x/y will not be a prime number, statement 3 false

Answer should be B
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no.prop 06 Jul 2011, 21:47
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The question for us to find what must be true... not what can true.


In your example X can be equal to Y, this is one scenario. Consider a more specific example of 15 and 5 for X and Y. All the criteria in the question are still satisfied. Hope this helps
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no.prop 07 Jul 2011, 00:48
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bagrettin
Take x=6, y=9. You have 3*6/9=2 which is a prime number.
Show more

3x/y is greater than 2. hence you cannot take x=6 and y=9.

Here's my take.

1) 3x/y = a , prime number greater than 2.
Now a prime number can have two factors only, 1 and number itself.
hence x/y = 1 , x=y. Must be true.

2) y=1. 3*3/1= 3, a prime number
3*4/4=3 here y=4. hence y=1 can or cannot be. So it's y=1 is not MUST.

3) x and y are prime integers.
3*5/5 = 3 , x and y are prime
3*6/6=3, x and y are not prime.
Hence x and y can or cannot be prime. So x and y is not MUST be prime.

I think OA should be B
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no.prop 07 Jul 2011, 06:05
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jamifahad
bagrettin
Take x=6, y=9. You have 3*6/9=2 which is a prime number.

3x/y is greater than 2. hence you cannot take x=6 and y=9.

Here's my take.

1) 3x/y = a , prime number greater than 2.
Now a prime number can have two factors only, 1 and number itself.
hence x/y = 1 , x=y. Must be true.

2) y=1. 3*3/1= 3, a prime number
3*4/4=3 here y=4. hence y=1 can or cannot be. So it's y=1 is not MUST.

3) x and y are prime integers.
3*5/5 = 3 , x and y are prime
3*6/6=3, x and y are not prime.
Hence x and y can or cannot be prime. So x and y is not MUST be prime.

I think OA should be B
Show more

whats if X = 7 and Y =3?
i think the OA is correct
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no.prop 07 Jul 2011, 06:07
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sudhir18n
whats if X = 7 and Y =3?
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Then you didn't read the question properly. :lol:
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no.prop 07 Jul 2011, 06:11
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jamifahad
sudhir18n
whats if X = 7 and Y =3?

Then you didn't read the question properly. :lol:
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My bad...
how abt X = 25 Y = 15
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no.prop 07 Jul 2011, 06:17
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Damn! You are right!! Thanks.
+1 for you.
OA is A then.
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no.prop 07 Jul 2011, 16:38
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3x/y can be 3 or 5 or 7 or 11......


I x =y is true when 3x/y =3 , but not in other cases

II y=1 need not be true . when 3x/y =3 => x=y

we can consider x=y=1 then y=1 is true

if we consider x=y=2 , then y is not equal to 1.

III x and y both need not be prime

when 3x/y =3 => x=y

x ,y can be 4 => they both are not prime

x,y can be 2 => they both are prime.

Answer is A (None)



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