NIELIT STA 2021

Question

Which of the following is true ? 

• A. $\log_{17} 275 = \log_{19} 375$
• B. $\log_{17} 275 > \log_{19} 375$
• C. $\log_{17} 275 < \log_{19} 375$
• D. None of these

Comments

option C

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how ?

Answer 1

let,

$\log_{17}275 =x$

so,$17^{x}=275$              …………….(1)

$\log_{19}375=y$

so,$19^{y}=375$               …………………...(2)

(1)$\div$(2)

$\frac{17^{x}}{19^{y}}=\frac{275}{375}< 1$

so,$17^{x}<19 ^{y}$

taking log both sides respect to base 19,

$x*\log_{19}17< y$

so, $\frac{x}{y}< 1$ ………..[as $\log_{17}19 > 1$]

so,$x< y$

 

[note ,

$\log_{17}275=1.984$

$\log_{19}375=2.012$

if you are allowed to use calculator which i believe you are not]