Difference between revisions of "2014 AMC 10A Problems/Problem 2"

(Solution)
 
(15 intermediate revisions by 8 users not shown)
Line 3: Line 3:
 
Roy's cat eats <math>\frac{1}{3}</math> of a can of cat food every morning and <math>\frac{1}{4}</math> of a can of cat food every evening. Before feeding his cat on Monday morning, Roy opened a box containing <math>6</math> cans of cat food. On what day of the week did the cat finish eating all the cat food in the box?
 
Roy's cat eats <math>\frac{1}{3}</math> of a can of cat food every morning and <math>\frac{1}{4}</math> of a can of cat food every evening. Before feeding his cat on Monday morning, Roy opened a box containing <math>6</math> cans of cat food. On what day of the week did the cat finish eating all the cat food in the box?
  
<math> \textbf{(A)}\ \text{Tuesday}\qquad\textbf{(B)}\ \text{Wednesday}\qquad\textbf{(C)}\ \text{Thursday}\qquad\textbf{(D)}}\ \text{Friday}\qquad\textbf{(E)}\ \text{Saturday}</math>
+
<math> \textbf{(A)}\ \text{Tuesday}\qquad\textbf{(B)}\ \text{Wednesday}\qquad\textbf{(C)}\ \text{Thursday}\qquad\textbf{(D)}\ \text{Friday}\qquad\textbf{(E)}\ \text{Saturday}</math>
  
== Solution ==
+
== Solution 1 ==
Each day, the cat eats <math>\dfrac13+\dfrac14=\dfrac7{12}</math> of a can of cat food. Therefore, the cat food will last for <math>\dfrac{6}{\dfrac7{12}}=\dfrac{72}7>10</math> days.
+
Each day, the cat eats <math>\dfrac13+\dfrac14=\dfrac7{12}</math> of a can of cat food. Therefore, the cat food will last for <math>\dfrac{6}{\frac7{12}}=\dfrac{72}7</math> days, which is greater than <math>10</math> days but less than <math>11</math> days.
Because the number of days is greater than 10, the cat will finish eating in 11 days, which is <math>4 \pmod 7</math>, so the cat will finish on <math>\textbf{(C)}</math> Thursday.
+
 
 +
 
 +
Because the number of days is greater than 10 and less than 11, the cat will finish eating in on the 11th day, which is equal to <math>10</math> days after Monday, or <math>\boxed{\textbf{(C)}\ \text{Thursday}}</math>
 +
 
 +
 
 +
== Solution 2 ==
 +
As above, the cat eats <math>\dfrac{7}{12}</math> of a can of cat food. Therefore we can write a table:
 +
 
 +
<cmath>\begin{array}{c|c|c|c|c|c|c}
 +
\text{Mon} & \text{Tue} & \text{Wed} & \text{Thu} & \text{Fri} & \text{Sat} & \text{Sun} \\
 +
\hline
 +
7/12 & 14/12 & 21/12 & 28/12 & 35/12 & 42/12 & 49/12 \\
 +
56/12 & 63/12 & 70/12 & 77/12 & 84/12 & 91/12 & 98/12
 +
\end{array}</cmath>
 +
 
 +
Since <math>6</math> cans of cat food is just <math>\dfrac{72}{12}</math> cans of cat food, then we see that the cat finished the sixth can of cat food on <math>\boxed{\text{Thursday} \ \textbf{(C)}}</math>
 +
 
 +
==Video Solution (CREATIVE THINKING)==
 +
https://youtu.be/hrin8SPWauU
 +
 
 +
~Education, the Study of Everything
 +
 
 +
 
 +
 
 +
 
 +
 
 +
==Video Solution==
 +
https://youtu.be/P9g1U4TQlUo
 +
 
 +
~savannahsolver
  
 
==See Also==
 
==See Also==
  
{{AMC10 box|year=2014|ab=A|before=2|num-a=3}}
+
{{AMC10 box|year=2014|ab=A|num-b=1|num-a=3}}
 
{{MAA Notice}}
 
{{MAA Notice}}
 +
 +
[[Category: Prealgebra Problems]]

Latest revision as of 12:33, 2 October 2023

Problem

Roy's cat eats $\frac{1}{3}$ of a can of cat food every morning and $\frac{1}{4}$ of a can of cat food every evening. Before feeding his cat on Monday morning, Roy opened a box containing $6$ cans of cat food. On what day of the week did the cat finish eating all the cat food in the box?

$\textbf{(A)}\ \text{Tuesday}\qquad\textbf{(B)}\ \text{Wednesday}\qquad\textbf{(C)}\ \text{Thursday}\qquad\textbf{(D)}\ \text{Friday}\qquad\textbf{(E)}\ \text{Saturday}$

Solution 1

Each day, the cat eats $\dfrac13+\dfrac14=\dfrac7{12}$ of a can of cat food. Therefore, the cat food will last for $\dfrac{6}{\frac7{12}}=\dfrac{72}7$ days, which is greater than $10$ days but less than $11$ days.


Because the number of days is greater than 10 and less than 11, the cat will finish eating in on the 11th day, which is equal to $10$ days after Monday, or $\boxed{\textbf{(C)}\ \text{Thursday}}$


Solution 2

As above, the cat eats $\dfrac{7}{12}$ of a can of cat food. Therefore we can write a table:

\[\begin{array}{c|c|c|c|c|c|c} \text{Mon} & \text{Tue} & \text{Wed} & \text{Thu} & \text{Fri} & \text{Sat} & \text{Sun} \\ \hline 7/12 & 14/12 & 21/12 & 28/12 & 35/12 & 42/12 & 49/12 \\ 56/12 & 63/12 & 70/12 & 77/12 & 84/12 & 91/12 & 98/12 \end{array}\]

Since $6$ cans of cat food is just $\dfrac{72}{12}$ cans of cat food, then we see that the cat finished the sixth can of cat food on $\boxed{\text{Thursday} \ \textbf{(C)}}$

Video Solution (CREATIVE THINKING)

https://youtu.be/hrin8SPWauU

~Education, the Study of Everything



Video Solution

https://youtu.be/P9g1U4TQlUo

~savannahsolver

See Also

2014 AMC 10A (ProblemsAnswer KeyResources)
Preceded by
Problem 1
Followed by
Problem 3
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 10 Problems and Solutions

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