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if x , y and z are integers and 2^x*5^y*z=0.00064, what is the value of xy?
1) z=20
2) x=-1
1) z=20
2) x=-1
Given: 2^x*5^y*z = 0.00064vaibhav101 wrote:if x , y and z are integers and 2^x*5^y*z=0.00064, what is the value of xy?
1) z=20
2) x=-1
=> 2^x*5^y*z = 64/10^5 = 2^6/10^5 = 2^6/(2^5*5^5) = 2*5^(-5)
=> 2^x*5^y*z = 2*5^(-5)
Let's take each statement one by one.
1) z = 20
We have 2^x*5^y*z = 2*5^(-5)
2^x*5^y*20 = 2*5^(-5)
2^x*5^y*(2^2*5) = 2*5^(-5)
2^(x+2)*5^(y+1) = 2*5^(-5)
=> x + 2 = 1 => x = -1 and y +1 = -5 => y = -6
=> xy = -1*-6 = 6. Sufficient.
2) x = -1
We do not have any information about z. Insufficient.
The correct answer: A
Hope this helps!
-Jay
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