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t=?

by grandh01 » Sun Aug 12, 2012 5:46 pm
What is the value of t ?
(1) The average (arithmetic mean) of
t2 and 8t is -8.
2) sqroot t^4=16

OA is A
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Source: — Data Sufficiency |
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by theCEO » Sun Aug 12, 2012 6:20 pm
grandh01 wrote:What is the value of t ?
(1) The average (arithmetic mean) of
t2 and 8t is -8.
2) sqroot t^4=16

OA is A
1.
(t2 + 8t)/2 = -8
t2 + 8t = -16
t(2+8)= -16
t = -16/10
sufficient

2.
sqroot t^4=16
t^4 = 16 * 16
t can be -4 or 4
insufficient

ans[spoiler]= a[/spoiler]
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