Logarithms Quiz Set 017

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Question 1

What is x if logx$(3/5)$ = $1/2$?

 A

${9/25}$.

 B

${3/5}$.

 C

$√{3/5}$.

 D

$√{5/3}$.

Soln.
Ans: a

logx$(3/5)$ = $1/2$, by definition, gives $x^{1/2}$ = $3/5$. So x = $(3/5)^2$ = ${9/25}$.


Question 2

What is log$4$ + log$1/4$?

 A

0.

 B

$\text"log"_3(4)$.

 C

$\text"log"_4(3)$.

 D

1/2.

Soln.
Ans: a

log(m) + log(1/m) = log (m × $1/m$) = log 1 = 0.


Question 3

What is the value of log2(128)?

 A

7.

 B

$√7$.

 C

0.

 D

$√128$.

Soln.
Ans: a

Let log2(128) = P. By definition, we have 2P = 128 = 27, which gives 7 as the answer.


Question 4

What is P if $\text"log"_5(4)$ + $\text"log"_5(4P + 1)$ = 1 + $\text"log"_5(P + 4)$?

 A

$1{5/11}$.

 B

$2{7/10}$.

 C

${5/13}$.

 D

$3{10/13}$.

Soln.
Ans: a

We have $\text"log"_5(4)$ + $\text"log"_5(4P + 1)$ = $\text"log"_5(5)$ + $\text"log"_5(P + 4)$. It is same as $\text"log"_5(4 × (4P + 1))$ = $\text"log"_5(5 × (P + 4))$. Equating the logs, $4 × (4P + 1) = 5 × (P + 4)$, solving for P we get P = $1{5/11}$.


Question 5

What is the value of log2(128)?

 A

7.

 B

$√7$.

 C

0.

 D

$√128$.

Soln.
Ans: a

Let log2(128) = P. By definition, we have 2P = 128 = 27, which gives 7 as the answer.


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This Blog Post/Article "Logarithms Quiz Set 017" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-06-24.

Posted by Parveen(Hoven),
Aptitude Trainer


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