Difference between revisions of "2018 AMC 8 Problems/Problem 1"

(Solution)
(27 intermediate revisions by 16 users not shown)
Line 1: Line 1:
 
==Problem 1==
 
==Problem 1==
An amusement park has a collection of scale models, with ratio <math>1 : 20</math>, of buildings and other sights from around the country. The height of the United States Capitol is 289 feet. What is the height in feet of its replica to the nearest whole number?
+
An amusement park has a collection of scale models, with a ratio <math> 1: 20</math>, of buildings and other sights from around the country. The height of the United States Capitol is 289 feet. What is the height in feet of its duplicate to the nearest whole number?
  
 
<math>\textbf{(A) }14\qquad\textbf{(B) }15\qquad\textbf{(C) }16\qquad\textbf{(D) }18\qquad\textbf{(E) }20</math>
 
<math>\textbf{(A) }14\qquad\textbf{(B) }15\qquad\textbf{(C) }16\qquad\textbf{(D) }18\qquad\textbf{(E) }20</math>
Line 7: Line 7:
  
  
You can set up a ratio: <math>\frac{1}{20}=\frac{x}{289}</math>. Cross multiplying, you get <math>20x=289</math>. You divide by 20 to get <math>x=14.45</math>. The closest integer is <math>\boxed{\textbf{(A)}14}</math>
+
You can set up a ratio: <math>\frac{1}{20}=\frac{x}{289}</math>. Cross multiplying, you get <math>20x=289</math>. You divide by <math>20</math> on each side to get <math>x=14.45</math>. The closest integer is <math>\boxed{\textbf{(A)}14}</math>
  
 
==Solution 2==
 
==Solution 2==
  
Alternatively, you can note that <math>20\cdot14</math> is <math>280</math>, and that <math>20\cdot15</math> is <math>300</math>. Since <math>289</math> is closer to <math>280</math>,the answer is <math>\boxed{\textbf{(A)}14}</math> ~ Mathscienceclass
+
 
 +
You can just do <math>\frac{289}{20}</math> and round your answer to get <math>\boxed{\textbf{(A)}14}</math>.
 +
It is basically Solution 1 without the ratio calculation, which might not be necessary.
 +
 
  
 
==See Also==
 
==See Also==

Revision as of 19:56, 18 April 2020

Problem 1

An amusement park has a collection of scale models, with a ratio $1: 20$, of buildings and other sights from around the country. The height of the United States Capitol is 289 feet. What is the height in feet of its duplicate to the nearest whole number?

$\textbf{(A) }14\qquad\textbf{(B) }15\qquad\textbf{(C) }16\qquad\textbf{(D) }18\qquad\textbf{(E) }20$

Solution 1

You can set up a ratio: $\frac{1}{20}=\frac{x}{289}$. Cross multiplying, you get $20x=289$. You divide by $20$ on each side to get $x=14.45$. The closest integer is $\boxed{\textbf{(A)}14}$

Solution 2

You can just do $\frac{289}{20}$ and round your answer to get $\boxed{\textbf{(A)}14}$. It is basically Solution 1 without the ratio calculation, which might not be necessary.


See Also

2018 AMC 8 (ProblemsAnswer KeyResources)
Preceded by
First Problem
Followed by
Problem 2
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