Mathematics · Quantitative Aptitude

Logarithms

246 Questions

Logarithms are mathematical operations that determine the exponent required for a base to reach a specific number. This topic tests the application of logarithmic properties, changing bases, and solving complex equations. It is a high-yield topic for quantitative aptitude in competitive exams.

Logarithmic expressionsBase change propertiesSolving log equationsInfinite series logsCharacteristic values

Logarithms Questions

Multiple choice general knowledge math & puzzles
  1. log 100

  2. 3

  3. 3 ln 10

  4. log? i don know.

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Given a = b = c = 10. Then x = log(a × b × c) = log(10 × 10 × 10) = log(1000). Using logarithm property: log(abc) = log(a) + log(b) + log(c) = log(10) + log(10) + log(10). Assuming base 10: log(10) = 1, so x = 1 + 1 + 1 = 3. The answer is 3, not log 100 or 3 ln 10.

Multiple choice general knowledge math & puzzles
  1. 450

  2. 8

  3. 1500

  4. 2

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To solve this problem, we need to understand the concept of logarithms and how they relate to exponents and exponentiation.

The problem states that the logarithm (base ten) of five hundred times an integer is three. We can write this information as:

log10(500x) = 3

To find the value of x, we need to isolate it on one side of the equation. We can do this by exponentiating both sides of the equation with base 10:

10^(log10(500x)) = 10^3

500x = 1000

Now, we can solve for x by dividing both sides of the equation by 500:

x = 1000/500

x = 2

Therefore, the correct answer is D. 2.

Multiple choice general knowledge math & puzzles
  1. A.P

  2. G.P

  3. H.P

  4. Non of these

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If x, y, z are in GP, then y² = xz, so 2log y = log x + log z. Let a = log x, b = log y, c = log z. Then 2b = a + c. For the sequence 1/(1+a), 1/(1+b), 1/(1+c) to be in HP, their reciprocals (1+a), (1+b), (1+c) must be in AP. Since 2(1+b) = 2 + 2b = 2 + a + c = (1+a) + (1+c), the reciprocals are in AP, so the original sequence is in HP.

Multiple choice general knowledge science & technology
  1. 0

  2. 1

  3. negative infinity

  4. infinity

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The logarithm of 0 is undefined in real numbers. As x approaches 0 from the positive side, log(x) approaches negative infinity because you're asking "what power must I raise the base to, to get 0?" - no real number works.

Multiple choice general knowledge science & technology
  1. 0

  2. 1

  3. infinity

  4. can not be determined

Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The logarithm of 1 is always 0 in any base, because any number raised to the power of 0 equals 1. This is a fundamental property of logarithms: log_b(1) = 0 for all bases b > 0, b ≠ 1.

Multiple choice general knowledge math & puzzles
  1. -3

  2. -5

  3. -7

  4. -1

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

First evaluate log10(1000) = 3, because 10^3 = 1000. The equation becomes 3 = 8 + v. Solving for v: v = 3 - 8 = -5. This problem tests knowledge of logarithms (log base 10 of 1000) combined with basic linear equation solving.

Multiple choice general knowledge math & puzzles
  1. 4(3+a)/(3-a)

  2. 2(3+a)/(3-a)

  3. 8(3+a)/(3-a)

  4. 4(3-a)/(3+a)

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given log27/log12 = a, we know log27 = log(3^3) = 3log3, and log12 = log(3×4) = log3 + log4 = log3 + 2log2. We need log16/log6 = log(2^4)/log(2×3) = 4log2/(log2+log3). Substituting and simplifying using the given ratio yields the answer 4(3-a)/(3+a). This requires logarithmic properties and algebraic manipulation.

Multiple choice technology architecture
  1. Dn = n log2n

  2. Dn = n log2n+1

  3. Dn = log2n

  4. Dn = log2n+1

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The depth of a complete binary tree is the number of levels from root to deepest leaf. For n nodes, the depth equals ⌊log₂n⌋ + 1 because a tree of depth d can hold at most 2^d - 1 nodes. This logarithmic relationship reflects how nodes double at each level in a perfect binary tree.