Difference between revisions of "1991 AHSME Problems/Problem 14"

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(A) <math>200</math>  (B) <math>201</math>  (C) <math>202</math>  (D) <math>203</math>  (E) <math>204</math>
 
(A) <math>200</math>  (B) <math>201</math>  (C) <math>202</math>  (D) <math>203</math>  (E) <math>204</math>
 
== Solution ==
 
== Solution ==
<math>\fbox{C}</math>
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Solution by e_power_pi_times_i
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Notice that if <math>x</math> is expressed in the form <math>a^b</math>, then the number of positive divisors of <math>x^3</math> is <math>3b+1</math>. Checking through all the answer choices, the only one that is in the form <math>3b+1</math> is <math>\boxed{\textbf{(C) } 202}</math>.
  
 
== See also ==
 
== See also ==

Revision as of 11:51, 13 December 2016

Problem

If $x$ is the cube of a positive integer and $d$ is the number of positive integers that are divisors of $x$, then $d$ could be

(A) $200$ (B) $201$ (C) $202$ (D) $203$ (E) $204$

Solution

Solution by e_power_pi_times_i


Notice that if $x$ is expressed in the form $a^b$, then the number of positive divisors of $x^3$ is $3b+1$. Checking through all the answer choices, the only one that is in the form $3b+1$ is $\boxed{\textbf{(C) } 202}$.

See also

1991 AHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 13
Followed by
Problem 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
All AHSME Problems and Solutions

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