LFM Pure and Mechanics

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csat-suneung 2005 Q15 4 marks Logarithmic Formula Application (Modeling) View
When sound passes through a building wall, a certain proportion is transmitted into the interior while the rest is reflected or absorbed. The ratio of sound transmitted into the interior is called the transmission rate. When the acoustic output of a speaker is $W$ (watts), the intensity $P$ (decibels) of sound transmitted into the interior at a distance of $r$ (m) from the speaker in a building with transmission rate $\alpha$ is as follows. $$\begin{aligned} & P = 10 \log \frac { \alpha W } { I _ { 0 } } - 20 \log r - 11 \\ & \text{(where } I _ { 0 } = 10 ^ { - 12 } \text{ (watts/m}^2\text{) and } r > 1 \text{.)} \end{aligned}$$ A speaker is emitting sound with an acoustic output of 100 (watts). When the intensity of sound transmitted into the interior of a building with transmission rate $\frac { 1 } { 100 }$ is 59 (decibels) or less, what is the minimum distance between the speaker and the building? (Assume that sound spreads uniformly in space and that factors other than transmission rate are not considered.) [4 points]
(1) $10 ^ { 2 } \mathrm{~m}$
(2) $10 ^ { \frac { 17 } { 8 } } \mathrm{~m}$
(3) $10 ^ { \frac { 13 } { 6 } } \mathrm{~m}$
(4) $10 ^ { \frac { 9 } { 4 } } \mathrm{~m}$
(5) $10 ^ { \frac { 5 } { 2 } } \mathrm{~m}$
csat-suneung 2005 Q19 3 marks Solve a Logarithmic Inequality View
Solve the system of inequalities $$\left\{ \begin{array} { l } \log _ { 3 } | x - 3 | < 4 \\ \log _ { 2 } x + \log _ { 2 } ( x - 2 ) \geqq 3 \end{array} \right.$$ and find the number of integers $x$ that satisfy it. [3 points]
csat-suneung 2005 Q19 3 marks Solve a Logarithmic Inequality View
System of inequalities $$\left\{ \begin{array} { l } \log _ { 3 } | x - 3 | < 4 \\ \log _ { 2 } x + \log _ { 2 } ( x - 2 ) \geqq 3 \end{array} \right.$$ Find the number of integers $x$ that satisfy the system. [3 points]
csat-suneung 2005 Q23 4 marks Simplify or Evaluate a Logarithmic Expression View
For a real number $a$ ($a > 1$), let $b = \sum _ { n = 1 } ^ { \infty } \left( \frac { 1 } { a } \right) ^ { n }$ be represented as in [Figure 1], and for a real number $c$, let $d = 16 ^ { c }$ be represented as in [Figure 2].
For the real numbers $x$, $y$, $z$ in the figure below, find the value of $\frac { x z } { y }$. [4 points]
csat-suneung 2005 Q27 4 marks Characteristic and Mantissa of Common Logarithms View
Let $a$ be the largest integer among numbers whose common logarithm characteristic is 2, and let $b$ be the smallest number among numbers whose common logarithm characteristic is $-2$. What is the value of $ab$? [4 points]
(1) 0.9
(2) 0.99
(3) 1
(4) 9.99
(5) 10
csat-suneung 2006 Q11 3 marks Characteristic and Mantissa of Common Logarithms View
For a positive number $a$, let the characteristic and mantissa of $\log a$ be $f ( a )$ and $g ( a )$ respectively. Which of the following in are correct? [3 points] 〈Remarks〉 ㄱ. $f ( 2006 ) = 3$ ㄴ. $g ( 2 ) + g ( 6 ) = g ( 12 ) + 1$ ㄷ. If $f ( a b ) = f ( a ) + f ( b )$, then $g ( a b ) = g ( a ) + g ( b )$.
(1) ㄱ
(2) ㄱ, ㄴ
(3) ㄱ, ㄷ
(4) ㄴ, ㄷ
(5) ㄱ, ㄴ, ㄷ
csat-suneung 2006 Q11 3 marks Characteristic and Mantissa of Common Logarithms View
For a positive number $a$, let the characteristic and mantissa of $\log a$ be $f ( a )$ and $g ( a )$ respectively. Which of the following statements in are true? [3 points]

ㄱ. $f ( 2006 ) = 3$ ㄴ. $g ( 2 ) + g ( 6 ) = g ( 12 ) + 1$ ㄷ. If $f ( a b ) = f ( a ) + f ( b )$, then $g ( a b ) = g ( a ) + g ( b )$.
(1) ㄱ
(2) ㄱ, ㄴ
(3) ㄱ, ㄷ
(4) ㄴ, ㄷ
(5) ㄱ, ㄴ, ㄷ
csat-suneung 2006 Q20 3 marks Solve a Logarithmic Equation View
For two positive numbers $a , b$, $$\left\{ \begin{array} { l } ab = 27 \\ \log _ { 3 } \frac { b } { a } = 5 \end{array} \right.$$ When these conditions hold, find the value of $4 \log _ { 3 } a + 9 \log _ { 3 } b$. [3 points]
csat-suneung 2006 Q24 4 marks Optimize a Logarithmic Expression View
For the function with domain $\{ x \mid 1 \leqq x \leqq 81 \}$, $$y = \left( \log _ { 3 } x \right) \left( \log _ { \frac { 1 } { 3 } } x \right) + 2 \log _ { 3 } x + 10$$ Let $M$ be the maximum value and $m$ be the minimum value. Find the value of $M + m$. [4 points]
csat-suneung 2006 Q25 4 marks Logarithmic Formula Application (Modeling) View
To remove bacteria living in a water tank, a chemical is to be administered. Let $C _ { 0 }$ be the initial number of bacteria per 1 mL of water in the tank, and let $C$ be the number of bacteria per 1 mL at time $t$ hours after the chemical is administered. The following relationship holds: $$\log \frac { C } { C _ { 0 } } = - k t \quad ( k \text { is a positive constant } )$$ The initial number of bacteria per 1 mL of water is $8 \times 10 ^ { 5 }$, and at time 3 hours after the chemical is administered, the number of bacteria per 1 mL becomes $2 \times 10 ^ { 5 }$. After $a$ hours from administering the chemical, the number of bacteria per 1 mL first becomes $8 \times 10 ^ { 3 }$ or less. Find the value of $a$. (Here, calculate using $\log 2 = 0.3$.) [4 points]
csat-suneung 2007 Q1 2 marks Simplify or Evaluate a Logarithmic Expression View
What is the value of $\left( \log _ { 3 } 27 \right) \times 8 ^ { \frac { 1 } { 3 } }$? [2 points]
(1) 12
(2) 10
(3) 8
(4) 6
(5) 4
csat-suneung 2007 Q1 2 marks Simplify or Evaluate a Logarithmic Expression View
The value of $\left( \log _ { 3 } 27 \right) \times 8 ^ { \frac { 1 } { 3 } }$ is? [2 points]
(1) 12
(2) 10
(3) 8
(4) 6
(5) 4
csat-suneung 2007 Q8 3 marks Simplify or Evaluate a Logarithmic Expression View
For three real numbers $a , b , c$ greater than 1, when $\log _ { a } c : \log _ { b } c = 2 : 1$, what is the value of $\log _ { a } b + \log _ { b } a$? [3 points]
(1) 1
(2) $\frac { 3 } { 2 }$
(3) 2
(4) $\frac { 5 } { 2 }$
(5) 3
csat-suneung 2007 Q13 4 marks Verify Truth of Logarithmic Statements View
For an integer $n$, two sets $A ( n ) , B ( n )$ are defined as $$\begin{aligned} & A ( n ) = \left\{ x \mid \log _ { 2 } x \leqq n \right\} \\ & B ( n ) = \left\{ x \mid \log _ { 4 } x \leqq n \right\} \end{aligned}$$ Which of the following statements in the given options are correct? [4 points] Given Options ㄱ. $A ( 1 ) = \{ x \mid 0 < x \leqq 1 \}$ ㄴ. $A ( 4 ) = B ( 2 )$ ㄷ. When $A ( n ) \subset B ( n )$, then $B ( - n ) \subset A ( - n )$.
(1) ㄱ
(2) ㄴ
(3) ㄷ
(4) ㄱ, ㄷ
(5) ㄴ, ㄷ
csat-suneung 2007 Q19 3 marks Solve a Logarithmic Equation View
For the logarithmic equation $\left( \log _ { 2 } x \right) ^ { 2 } - 4 \log _ { 2 } x = 0$, let the two roots be $\alpha , \beta$ respectively. Find the value of $\alpha + \beta$. [3 points]
csat-suneung 2007 Q27 4 marks Characteristic and Mantissa of Common Logarithms View
For $a$ with $0 < a < 1$, when $10 ^ { a }$ is divided by 3, the quotient is an integer and the remainder is 2. What is the sum of all values of $a$? [4 points]
(1) $3 \log 2$
(2) $6 \log 2$
(3) $1 + 3 \log 2$
(4) $1 + 6 \log 2$
(5) $2 + 3 \log 2$
csat-suneung 2008 Q1 2 marks Simplify or Evaluate a Logarithmic Expression View
What is the value of $8 ^ { \frac { 2 } { 3 } } + \log _ { 2 } 8$? [2 points]
(1) 5
(2) 6
(3) 7
(4) 8
(5) 9
csat-suneung 2008 Q1 2 marks Simplify or Evaluate a Logarithmic Expression View
The value of $8 ^ { \frac { 2 } { 3 } } + \log _ { 2 } 8$ is? [2 points]
(1) 5
(2) 6
(3) 7
(4) 8
(5) 9
csat-suneung 2008 Q16 4 marks Logarithmic Function Graph Intersection or Geometric Analysis View
The line $y = 2 - x$ intersects the graphs of the two logarithmic functions $y = \log _ { 2 } x$ and $y = \log _ { 3 } x$ at points $\left( x _ { 1 } , y _ { 1 } \right)$ and $\left( x _ { 2 } , y _ { 2 } \right)$, respectively. Which of the following in are correct? [4 points]
ㄱ. $x _ { 1 } > y _ { 2 }$ ㄴ. $x _ { 2 } - x _ { 1 } = y _ { 1 } - y _ { 2 }$ ㄷ. $x _ { 1 } y _ { 1 } > x _ { 2 } y _ { 2 }$
(1) ㄱ
(2) ㄷ
(3) ㄱ, ㄴ
(4) ㄴ, ㄷ
(5) ㄱ, ㄴ, ㄷ
csat-suneung 2008 Q19 3 marks Solve a Logarithmic Inequality View
Find the maximum natural number $x$ that satisfies the inequality $\left( \log _ { 3 } x \right) \left( \log _ { 3 } 3 x \right) \leqq 20$. [3 points]
csat-suneung 2008 Q22 4 marks Logarithmic Formula Application (Modeling) View
The average number of earthquakes $N$ with magnitude $M$ or greater occurring in a region over one year satisfies the following equation.
$$\log N = a - 0.9 M ( \text{ where } a \text{ is a positive constant } )$$
In this region, earthquakes with magnitude 4 or greater occur on average 64 times per year. Earthquakes with magnitude $x$ or greater occur on average once per year. Find the value of $9 x$. (Use $\log 2 = 0.3$ for the calculation.) [4 points]
csat-suneung 2008 Q30 4 marks Characteristic and Mantissa of Common Logarithms View
For a two-digit natural number $N$, when the mantissa of $\log N$ is $\alpha$,
$$\frac { 1 } { 2 } + \log N = \alpha + \log _ { 4 } \frac { N } { 8 }$$
Find the value of $N$ that satisfies this equation. [4 points]
csat-suneung 2009 Q4 3 marks Optimize a Logarithmic Expression View
What is the minimum value of the function $y = 3 + \log _ { 3 } \left( x ^ { 2 } - 4 x + 31 \right)$? [3 points]
(1) 4
(2) 5
(3) 6
(4) 7
(5) 8
csat-suneung 2009 Q6 3 marks Simplify or Evaluate a Logarithmic Expression View
When $a = \log _ { 2 } 10 , b = 2 \sqrt { 2 }$, what is the value of $a \log b$? [3 points]
(1) 1
(2) $\frac { 3 } { 2 }$
(3) 2
(4) $\frac { 5 } { 2 }$
(5) 3
csat-suneung 2009 Q11 4 marks Verify Truth of Logarithmic Statements View
For a constant $a$ with $0 < a < \frac { 1 } { 2 }$, let the point where the line $y = x$ meets the curve $y = \log _ { a } x$ be $( p , p )$, and let the point where the line $y = x$ meets the curve $y = \log _ { 2 a } x$ be $( q , q )$. Which of the following statements in $\langle$Remarks$\rangle$ are correct? [4 points]
$\langle$Remarks$\rangle$ ㄱ. If $p = \frac { 1 } { 2 }$, then $a = \frac { 1 } { 4 }$. ㄴ. $p < q$ ㄷ. $a ^ { p + q } = \frac { p q } { 2 ^ { q } }$
(1) ㄱ
(2) ㄱ, ㄴ
(3) ㄱ, ㄷ
(4) ㄴ, ㄷ
(5) ㄱ, ㄴ, ㄷ