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a + b <= 1

Expert replies
Source: — Data Sufficiency |

by nicktimoshenko » Thu May 20, 2010 11:45 pm
colakumarfanta wrote:Is a + b <= 1?
1) a ^ 2 + b ^ 2 <= 1
2) a ^ 2-b ^ 2 <= 1
Е

statement B: 0,51*0,51*0,51*0,51 <=1

A: 0.51*0.51*2<=1

but 0.51*2 >1
first attempt 540 (Q48 V17)
second attempt 610 (q47 v27)
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by arohan_sambyal » Fri May 21, 2010 5:17 am
Statement i
a=0.6=b, satisfies choice A and a+b>=1
a=-0.6=b, satisfies choice A and a+b<=1
Therefore statement 1 Is not sufficient
Statement ii
a^2-b^2=(a+b)(a-b)<=1 ,
a=0.6 and b =0.7 , a^2-b^2<=1 and a+b>=1
a=0.5 and b=0.1, a^2-b^2<=1 and a+b<=1
therefore statement 2 is not sufficient

ANSWER : CHOICE E
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by nicktimoshenko » Fri May 21, 2010 5:27 am
arohan_sambyal wrote:Statement i
a=0.6=b, satisfies choice A and a+b>=1
a=-0.6=b, satisfies choice A and a+b<=1
Therefore statement 1 Is not sufficient
Statement ii
a^2-b^2=(a+b)(a-b)<=1 , can happen only if (a+b)<=1
So statement 2 is sufficeint

ANSWER : CHOICE B
agree

I mistook "-"for "*"
first attempt 540 (Q48 V17)
second attempt 610 (q47 v27)
my blog:
https://waytotopbs.blocked
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