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29 Dec 2017, 10:17
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D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
69% (01:47) correct
31%
(01:33)
wrong
based on 89
sessions
History
Date
Time
Result
Not Attempted Yet
If a is a positive integer and \(y = 3.2\) x \(10^a\), what is the value of y?
1. \(400 < y < 30,000\)
2. \(y^2\) \(=\) \(1.024\) x \(10^7\)
1. \(400 < y < 30,000\)
2. \(y^2\) \(=\) \(1.024\) x \(10^7\)
29 Dec 2017, 10:28
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QZ
Statement I 400<y<30,000 has only 3200 in the range..
320 is less and 32000 is more, so y =3200
Sufficient
Statement II..
Don't waste time in calculating value of y..
Here y will have two values one POSITIVE and other NEGATIVE..
But we are looking for only POSITIVE..
So sufficient
D
29 Dec 2017, 10:32
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QZ
Statement 1: \(a\) cannot be \(1\) or \(2\) because in that case \(y=32\) or \(320 <400\) not possible
\(a\) cannot be \(4\) because in that case \(y=32000>30000\) not possible
so \(a=3\) hence \(y=3.2*10^3\). Sufficient
Statement 2: we know \(a\) is positive so \(y>0\)
Take the square root of \(y^2\) and as negative value of \(y\) is not possible so we have only one value for \(y\). Sufficient
Option D
