Difference between revisions of "2020 AMC 12A Problems/Problem 1"

(Solution)
(Solution 1)
Line 7: Line 7:
 
==Solution 1==
 
==Solution 1==
  
If Carlos took 70% of the pie, (100 - 70) = 30% must be remaining. After Maria takes 1/3 of the remaining 30%,  
+
If Carlos took <math>70\%</math> of the pie, <math>(100 - 70) = 30\%</math> must be remaining. After Maria takes <math>\frac{1}{3}</math> of the remaining <math>30\%, </math>
(1 - 1/3) = 2/3 is left.
+
<math>1 - \frac{1}{3} = \frac{2}{3}</math> is left.
  
 
Therefore:
 
Therefore:
  
(3 / 10) * (2 / 3) = (2 / 10) = 20%, which is answer choice C
+
<math>\frac{3}{10} \cdot \frac{2}{3} = \frac{2}{10}= \boxed{\textbf{C) }20\%}</math>
  
If anyone could add the latex to the numbers / expressions that would be really helpful!
+
-Contributed by Awesome2.1, latex by quacker88
 
 
-Contributed by Awesome2.1
 
  
 
==See Also==
 
==See Also==

Revision as of 11:00, 1 February 2020

Problem

Carlos took $70\%$ of a whole pie. Maria took one third of the remainder. What portion of the whole pie was left?

$\textbf{(A)}\ 10\%\qquad\textbf{(B)}\ 15\%\qquad\textbf{(C)}\ 20\%\qquad\textbf{(D)}\ 30\%\qquad\textbf{(E)}\ 35\%$

Solution 1

If Carlos took $70\%$ of the pie, $(100 - 70) = 30\%$ must be remaining. After Maria takes $\frac{1}{3}$ of the remaining $30\%,$ $1 - \frac{1}{3} = \frac{2}{3}$ is left.

Therefore:

$\frac{3}{10} \cdot \frac{2}{3} = \frac{2}{10}= \boxed{\textbf{C) }20\%}$

-Contributed by Awesome2.1, latex by quacker88

See Also

2020 AMC 12A (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 AMC 12 Problems and Solutions

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