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Inequation DS

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Inequation DS

by FC » Tue Apr 20, 2010 6:07 am
What is the value of integer s ?

(1) 4 < (s-1)*(s-1) < 16
(2) 4 < (s+1)*(s-1) < 16

OA is C

Could you please share your reasoning on this one ?

Thanks,
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by ajith » Tue Apr 20, 2010 6:13 am
FC wrote:What is the value of integer s ?

(1) 4 < (s-1)*(s-1) < 16
(2) 4 < (s+1)*(s-1) < 16

OA is C

Could you please share your reasoning on this one ?

Thanks,
1) since s is an integer

(s-1)^2 is an perfect square and integer

between 16 and 4 there is only 9 as the perfect square integer

(s-1)^2 = 9 => s-1 = +/-3 s= -2 or 4

Insufficient

2) s^2 -1 is in between 4 and 16
s^2 is in between 5 and 17
s^2 is either 16 or 9

s is +/-4 or +/-3

Insufficient

Combining,
s = 4 is the only option, sufficient
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by asfa » Tue Apr 20, 2010 6:26 am
IMO E

st1...4 and -2 satisfies this equation
st2 -4, 3, and -3 satisfies this equation

combine there are 5 possibilities
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by akdayal » Tue Apr 20, 2010 8:42 am
IMO E

st1...4 and -2 satisfies this equation
st2 -4, 3, and -3 satisfies this equation

combine there are 5 possibilities
why are you combine the solution??
Take intersection not union.
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