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If x is an integer, is 3^x less than 500? [#permalink]
 28 Oct 2012, 15:31
Question Stats:
33% (02:25) correct
66% (01:51) wrong based on 0 sessions
If x is an integer, is 3^x less than 500? (1) 4^(x–1) < 4^x – 120 (2) x^2 = 36
Last edited by Bunuel on 29 Oct 2012, 04:18, edited 1 time in total.
Renamed the topic and edited the question.
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Re: Inequality problem [#permalink]
28 Oct 2012, 22:21
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himanshuhpr wrote: If x is an integer, is 3x less than 500?
(1) 4^(x–1) < 4^x – 120
(2) x^2 = 25
OA: C
From (1) we get x>4
From (2) we get x= +5 -5
It Should be B why its C ?? The answer IS B. If OA is given as C, then it is wrong. Kudos Please... If my post helped.
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Re: Inequality problem [#permalink]
29 Oct 2012, 01:31
yup. i also got B..
Lets C..wat experts r replying !!
can anyone tell me trick for this thing..
4^x-4^x-1=120..how to get comon ..i did it.. but i tuk me more than one mint
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Re: Inequality problem [#permalink]
29 Oct 2012, 01:59
Statement 1 --> 120 < \frac{3}{4}*4^x ==> 160 < 4^x ==> therefore, x > 3 ==> Insufficient. Statement 2 --> x = +5 or -5 ==> therefore, 3x is either +15 or -15 in both cases its less than 500 ==> Sufficient. Answer : B
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Director
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Re: Inequality problem [#permalink]
29 Oct 2012, 02:34
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sanjoo wrote: yup. i also got B..
Lets C..wat experts r replying !!
can anyone tell me trick for this thing..
4^x-4^x-1=120..how to get comon ..i did it.. but i tuk me more than one mint 4^x -4^(x-1) = 1204^x - \frac{4^x}{4} = 120\frac{3}{4}*4^x = 120Kudos Please... If my post helped.
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Re: Inequality problem [#permalink]
29 Oct 2012, 04:18
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himanshuhpr wrote: If x is an integer, is 3x less than 500?
(1) 4^(x–1) < 4^x – 120
(2) x^2 = 25
OA: C
From (1) we get x>4
From (2) we get x= +5 -5
It Should be B why its C ?? The question should read: If x is an integer, is 3^x less than 500? Since 3^6=729>500 and 3^5=243<500, then the question basically asks whether x is an integer less than 6 (5, 4, 3, 2, 1, 0, -1, ...). (1) 4^(x–1) < 4^x – 120 --> \frac{4^x}{4}<4^x-120 --> 120<\frac{3}{4}*4^x --> 160<4^x --> x is an integer greater than 3: 4, 5, 6, 7, ... Not sufficient. (2) x^2 = 36 --> x=6 or x=-6. Not sufficient. (1)+(2) From above x=6, thus the answer to the question is NO. Sufficient. Answer: C. Similar questions to practice: is-x-10-10-1-x-2-34-2-x-127881.htmlis-5-k-less-than-1-000-1-5-k-128055.htmlif-x-is-an-integer-and-4-x-100-what-is-x-1-4-x-106353.htmlis-4-x-5-3x-1-1-x-is-an-integer-86765.htmlis-5-x-134898.htmlis-3-x-134968.htmlHope it helps.
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Re: Inequality problem
[#permalink]
29 Oct 2012, 04:18
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