Smeagol's Genius Game

Smeagol is a very brilliant creature! In his spare time, he figured out that log 3 5 = 1.465 \log_35 = 1.465 without any calculators! With this brilliant knowledge, he decided to play a "game" with Bilbo Baggins, who is lost in Smeagol's cave. In this "game", Bilbo has to find the smallest b b such that 3 b > 5 360 3^b > 5^{360} . If Bilbo finds the correct b b , Smeagol must lead him out of the cave. Otherwise, Bilbo becomes Smeagol's lunch. What b b should Bilbo choose to guarantee his safe passage out of the cave?


The answer is 528.

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6 solutions

log 3 5 = 1.465 3 1.465 = 5 \log_{3}{5}=1.465 \implies 3^{1.465}=5

( 3 1.465 ) 360 = 5 360 (3^{1.465})^{360}=5^{360}

3 527.4 = 5 360 3^{527.4}=5^{360}

Hence, the smallest b b is 528 \boxed {528}

Hello,

as given that creature smeagol knew that log 5 base 3 = 1.465,

so,

3^(b) > 5 ^ 360

3^(b) = 5^(360)

b log 3 = 360 log 5, make the equation to base 3,

b log 3 base 3 = 360 log 5 base 3,

b(1) = 360 (1.465)

b = 527.4, remember that the condition,

3^(b) > 5^(360),

therefore b > 527.4 = 528 (the closest to get the value)...

thanks...

Syed Hamza
Mar 30, 2014

My computer program for this: long double a, b; a = pow(5, 360); for (b = 0; b < 1000; b++) { if (pow(3, b)>a) { cout << b<<endl; break; } }

Saurav Pal
Mar 26, 2014

3^b > 5^360,
b log 3 > 360 log 5,
b > 360*1.465,
b = 528.


Shreyas Shastry
Mar 19, 2014

log 5 to base 3=1.465

so 3^1.465=5

now express 3^b>5^360 as power of b

so 3^b>(3^1.465)^360

so 3^b>3^527.4

so nearest integer power greater than 527.24 is 528

so the answer is 528

Abishek Hariharan
Mar 14, 2014

360*1.465=527.4 So, the smallest integer greater than 527.4 is 528.

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