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^ 3 * y ^

by sanju09 » Thu Mar 26, 2009 6:14 am
If x ^ 3 * y ^ 4 = 5,000, is y = 5?

(1) y is a positive integer.
(2) x is an integer.
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by goelmohit2002 » Thu Mar 26, 2009 7:29 am
If x ^ 3 * y ^ 4 = 5,000, is y = 5?

(1) y is a positive integer.
(2) x is an integer.

Taking 1 alone
y can be 1, 2, 3....or any number...as we do not know anything about x.

Taking 2 alone
x can be both say 1 and 2...since we do not know anything about y.

Combining 1 and 2.
since y ^ 4 = Always +ve so and R.H.S = +ve...so x has to be positive
now 5000 = 2 * 2 * 2 * 5 * 5 * 5 * 5

Since both x and y are positive integers, so only way is x = 2 and y = 5.

So IMO "c" should be the answer.

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Re: ^ 3 * y ^

by mjjking » Thu Mar 26, 2009 7:33 am
sanju09 wrote:If x ^ 3 * y ^ 4 = 5,000, is y = 5?

(1) y is a positive integer.
(2) x is an integer.
IMO A.

We know that x ^ 3 * y ^ 4 = 5,000 (i.e. 2^3*5^4).

If from 1. we know that y is positive, x MUST be positive as well. hence we can deduct that y=5.
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Re: ^ 3 * y ^

by goelmohit2002 » Thu Mar 26, 2009 7:37 am
mjjking wrote:
sanju09 wrote:If x ^ 3 * y ^ 4 = 5,000, is y = 5?

(1) y is a positive integer.
(2) x is an integer.
IMO A.

We know that x ^ 3 * y ^ 4 = 5,000 (i.e. 2^3*5^4).

If from 1. we know that y is positive, x MUST be positive as well. hence we can deduct that y=5.
A says that Y is positive...but tells nothing about "X"....Here Y can be 1, 2, 3, 4, 5...or in my opinion any positive number....

X can be real too.
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by sanju09 » Fri Mar 27, 2009 3:30 am
Mohit
Combining 1 and 2.
since y ^ 4 = Always +ve so and R.H.S = +ve...so x has to be positive
now 5000 = 2 * 2 * 2 * 5 * 5 * 5 * 5

Mjjking
We know that x ^ 3 * y ^ 4 = 5,000 (i.e. 2^3*5^4).

If from 1. we know that y is positive, x MUST be positive as well. hence we can deduct that y=5.

Mohit
A says that Y is positive...but tells nothing about "X"....Here Y can be 1, 2, 3, 4, 5...or in my opinion any positive number....

X can be real too.
Mohit could realize that x is positive, only after taking the two statements together. Can any one realize the same without using either statement?

Mjjking believes that if x ^ 3 * y ^ 4 = 5,000 then it is granted that it is none other than 2^3*5^4, without using any statement. Can any one rebuff his belief?

Statement 1, not A says that Y is positive, and it further calls y an integer too. How can one exploit the given situation to its maximum, if one tends to take the granted for granted? All numbers (literals/numerals) used on GMAT are real. So if there is an x, it is real, not it can be real too!
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by goelmohit2002 » Fri Mar 27, 2009 4:38 am
sanju09 wrote: Mohit could realize that x is positive, only after taking the two statements together. Can any one realize the same without using either statement?
Yes you are right....we do not need to combine both statement to come to conclusion that X is +ve...since R.H.S is +ve and y has no effect..so X has to be +Ve.
sanju09 wrote: Mjjking believes that if x ^ 3 * y ^ 4 = 5,000 then it is granted that it is none other than 2^3*5^4, without using any statement. Can any one rebuff his belief?
IMO both the below satisifies if we just use "A":
a) x = (5000)^(1/3) and y =1
b) x = 2 and y = 5
sanju09 wrote: Statement 1, not A says that Y is positive, and it further calls y an integer too. How can one exploit the given situation to its maximum, if one tends to take the granted for granted? All numbers (literals/numerals) used on GMAT are real. So if there is an x, it is real, not it can be real too!
Can you please write the above statement in a bit more simpler language.....
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