Difference between revisions of "2011 AMC 12A Problems/Problem 1"

(Problem)
m (Solution)
 
(12 intermediate revisions by 9 users not shown)
Line 1: Line 1:
 
== Problem ==
 
== Problem ==
A cell phone plan costs $20 each month, plus 5 cents per text message sent, plus 10 cents for each minute used over 30 hours. In January Michelle sent 100 text messages and talked for 30.5 hours. How much did she have to pay?
+
A cell phone plan costs <math>20</math> dollars each month, plus <math>5</math> cents per text message sent, plus <math>10</math> cents for each minute used over <math>30</math> hours. In January Michelle sent <math>100</math> text messages and talked for <math>30.5</math> hours. How much did she have to pay?
 +
 +
<math>
 +
\textbf{(A)}\ 24.00 \qquad
 +
\textbf{(B)}\ 24.50 \qquad
 +
\textbf{(C)}\ 25.50 \qquad
 +
\textbf{(D)}\ 28.00 \qquad
 +
\textbf{(E)}\ 30.00 </math>
 +
 
  
 
== Solution ==
 
== Solution ==
 +
The base price of Michelle's cell phone plan is <math>20</math> dollars.
 +
If she sent <math>100</math> text messages and it costs <math>5</math> cents per text, then she must have spent <math>500</math> cents for texting, or <math>5</math> dollars. She talked for <math>30.5</math> hours, but <math>30.5-30</math> will give us the amount of time exceeded past 30 hours.
 +
<math>30.5-30=.5</math> hours <math>=30</math> minutes.
 +
Since the price for phone calls is <math>10</math> cents per minute, the additional amount Michelle has to pay for phone calls is <math>30*10=300</math> cents, or <math>3</math> dollars.
 +
Adding <math>20+5+3</math> dollars <math>\boxed{\$28 \textbf{ (D)}}</math>.
 +
 +
==Video Solution==
 +
https://youtu.be/tWz5T2Db9AY
 +
 +
~savannahsolver
 +
 
== See also ==
 
== See also ==
 
{{AMC12 box|year=2011|before=First Problem|num-a=2|ab=A}}
 
{{AMC12 box|year=2011|before=First Problem|num-a=2|ab=A}}
 +
{{AMC10 box|year=2011|before=First Problem|num-a=2|ab=A}}
 +
{{MAA Notice}}

Latest revision as of 11:09, 19 October 2023

Problem

A cell phone plan costs $20$ dollars each month, plus $5$ cents per text message sent, plus $10$ cents for each minute used over $30$ hours. In January Michelle sent $100$ text messages and talked for $30.5$ hours. How much did she have to pay?

$\textbf{(A)}\ 24.00 \qquad \textbf{(B)}\ 24.50 \qquad \textbf{(C)}\ 25.50 \qquad \textbf{(D)}\ 28.00 \qquad \textbf{(E)}\ 30.00$


Solution

The base price of Michelle's cell phone plan is $20$ dollars. If she sent $100$ text messages and it costs $5$ cents per text, then she must have spent $500$ cents for texting, or $5$ dollars. She talked for $30.5$ hours, but $30.5-30$ will give us the amount of time exceeded past 30 hours. $30.5-30=.5$ hours $=30$ minutes. Since the price for phone calls is $10$ cents per minute, the additional amount Michelle has to pay for phone calls is $30*10=300$ cents, or $3$ dollars. Adding $20+5+3$ dollars $\boxed{$28 \textbf{ (D)}}$.

Video Solution

https://youtu.be/tWz5T2Db9AY

~savannahsolver

See also

2011 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
2011 AMC 10A (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 10 Problems and Solutions

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