Difference between revisions of "1993 AJHSME Problems/Problem 3"

(Created page with '==Problem== Which of the following numbers has the largest prime factor? <math> \text{(A)}\ 39\qquad\text{(B)}\ 51\qquad\text{(C)}\ 77\qquad\text{(D)}\ 91\qquad\text{(E)}\ 121 <…')
 
(Solution)
 
(4 intermediate revisions by 4 users not shown)
Line 9: Line 9:
 
B. The prime factors of <math>51</math> are <math>3</math> and <math>17</math>. Therefore, the largest prime factor is <math>17</math>.
 
B. The prime factors of <math>51</math> are <math>3</math> and <math>17</math>. Therefore, the largest prime factor is <math>17</math>.
  
C. The prime factors of <math>77</math> are <math>7</math> and <math>11</math>. Therefore, the largest prime factor is <math>11</math>.
+
C. The prime factor of <math>77</math> are <math>7</math> and <math>11</math>. Therefore, the largest prime factor is <math>11</math>.
  
D. The prime factors of <math>91</math> are <math>7</math> and <math>13</math>. Therefore, the largest prime factor is <math>13</math>.  
+
D. The prime factor of <math>91</math> are <math>7</math> and <math>13</math>. Therefore, the largest prime factor is <math>13</math>.
  
E. The only prime factor of <math>121</math> is <math>11</math>. This makes <math>11</math> the largest prime factor of this number.  
+
E. The prime factor of <math>121</math> are <math>11</math>. Therefore, the largest prime factor is <math>11</math>.
  
Since we are looking for the number with the largest prime factor, the correct answer would be <math>\boxed{B}</math>
+
So, the answer is <math>B</math>
 +
 
 +
==See Also==
 +
 
 +
{{AJHSME box|year=1993|num-b=2|num-a=4}}
 +
{{MAA Notice}}

Latest revision as of 13:27, 27 November 2022

Problem

Which of the following numbers has the largest prime factor?

$\text{(A)}\ 39\qquad\text{(B)}\ 51\qquad\text{(C)}\ 77\qquad\text{(D)}\ 91\qquad\text{(E)}\ 121$

Solution

A. The prime factors of $39$ are $3$ and $13$. Therefore, the largest prime factor is $13$.

B. The prime factors of $51$ are $3$ and $17$. Therefore, the largest prime factor is $17$.

C. The prime factor of $77$ are $7$ and $11$. Therefore, the largest prime factor is $11$.

D. The prime factor of $91$ are $7$ and $13$. Therefore, the largest prime factor is $13$.

E. The prime factor of $121$ are $11$. Therefore, the largest prime factor is $11$.

So, the answer is $B$

See Also

1993 AJHSME (ProblemsAnswer KeyResources)
Preceded by
Problem 2
Followed by
Problem 4
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
All AJHSME/AMC 8 Problems and Solutions

The problems on this page are copyrighted by the Mathematical Association of America's American Mathematics Competitions. AMC logo.png