CA Foundation · Quantitative Aptitude · Ratio and Proportion, Indices and Logarithms
The value of log₅ 1 + log₇ 7 + log₁₀ 0.01 is:
The value is -1. Since log₅ 1 equals 0, log₇ 7 equals 1, and log₁₀ 0.01 equals -2 because 0.01 is 10 to the power -2, the sum is 0 + 1 - 2 = -1.
- A-1Correct
- B0
- C1
- D2
Explanation
log₅ 1 = 0 because any base raised to power 0 gives 1. log₇ 7 = 1. log₁₀ 0.01 = log₁₀ 10⁻² = -2. Sum = 0 + 1 - 2 = -1. Taking log₁₀ 0.01 as 2 (ignoring the negative sign) would give 3, and treating log₅ 1 as 1 would give 0, both wrong.
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