COMEDK · Maths · 1. Basic of Mathematics
If \(\log _{10} 7=0.8451\), then the position of the first significant figure of \(7^{-20}\) is
- A 16
- B 17
- C 20
- D 15
Answer & Solution
Correct Answer
(B) 17
Step-by-step Solution
Detailed explanation
We have, \[ \begin{aligned} &\qquad \log _{10} 7=0.8451 \\ &\text { Let } \quad x=7^{-20} \\ &\Rightarrow \log x=-20 \log 7=-20 \times 0.8451=-16.902 \\ &\Rightarrow x=10^{-16.902} \end{aligned} \] Now, \(-16.902\) lies between \(-16\) and \(-17\) So, position of first…
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