Logarithms Quiz Set 002

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Question 1

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

 A

${3/5}$.

 B

${9/25}$.

 C

$√{3/5}$.

 D

$√{5/3}$.

Soln.
Ans: a

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


Question 2

What is the value of $\text"log"_4(√4)$?

 A

$1/2$.

 B

$2$.

 C

$\text"log"_√4(4)$.

 D

0.

Soln.
Ans: a

From the theory of logarithms, we know that $\text"log"_m(√m)$ = $1/2$ × $\text"log"_m(m)$ = $1/2$ × 1 = 1/2.


Question 3

If log(125) = 3, what is log(25)?

 A

2.

 B

$\text"log"_25(5)$.

 C

$\text"log"_5(125)$.

 D

1/2.

Soln.
Ans: a

We have 3 = log125 = log$5^3$ = 3 log 5, which gives log5 = 1. So, 2 = 2 × log5 = log$5^2$ = log25. Hence, the answer is 2.


Question 4

What is ${\text"log"(√7)}/{\text"log"(7)}$?

 A

1/2.

 B

$\text"log"_7(√7)$.

 C

$\text"log"_√7(7)$.

 D

2.

Soln.
Ans: a

${\text"log"(√7)}/{\text"log"(7)}$ is same as ${\text"log"(7^{1/2})}/{\text"log"(7)}$, which is same as (1/2) × ${\text"log"(7)}/{\text"log"(7)}$ = 1/2.


Question 5

If log(125) = 3, what is log(25)?

 A

2.

 B

$\text"log"_25(5)$.

 C

$\text"log"_5(125)$.

 D

1/2.

Soln.
Ans: a

We have 3 = log125 = log$5^3$ = 3 log 5, which gives log5 = 1. So, 2 = 2 × log5 = log$5^2$ = log25. Hence, the answer is 2.


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Creative Commons License
This Blog Post/Article "Logarithms Quiz Set 002" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-05-17.

Posted by Parveen(Hoven),
Aptitude Trainer


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