Latest Elitmus Aptitude Question SOLUTION: if logN base3+logN base9,sum is whole number,then how many number possible for N between 100 to 100? A)1 B)20 C)111 D)i didn't remember

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(#M40154116) ELITMUS Numerical Ability question apptitude Keep an EYE

if logN base3+logN base9,sum is whole number,then how many number possible for N between 100 to 100?
A)1
B)20
C)111
D)i didn't remember

Asked In Elitmus KIRAN (8 years ago)

Unsolved Read Solution (5)

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Read Solution (5) :

Anjai Baghel  (8 years ago)

ans =1

N value should be in between 10 to 100

log 81 base 3 + log 81 base 9 is possible

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LAV KUMAR  (8 years ago)

answer should be option (A)
we can write logN base3=(logN baseX/log3 baseX);
and logN base9=(logN baseX/log9 baseX);
now, logN base3+logN base9= ( logN baseX / log3 baseX + logN baseX / log9 baseX)
=logN baseX (1/log3 baseX + 1/2log3 baseX) bcz (3 square =9)
=logN baseX ( 3log3 baseX / 2log3 baseX *log3 baseX) by simple addition
=logN base X ( 3/2log3 base X)
or =logN base X *3 / log9 base X
or =3 * logN base 9:
so N should be 81 because it is a 9 square and it also ies between 10 to 100.

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Akshay  (8 years ago)

answer should be 2
since log(9)+log(9)=3 for base 3 and 9 respectively
log 81+ log 81=6 for base 3 and 9 respectively

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Roushan  (8 years ago)

ans=1 because 81 is only value between 10 to 100

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Abhishek  (8 years ago)

@akshay value must be in range {10 to 100 }

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