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

(Solution)
m (Solution)
 
(6 intermediate revisions by 6 users not shown)
Line 11: Line 11:
  
 
== Solution ==
 
== Solution ==
The base price of Michelle's cell phone plan is <dollar/>20.  
+
The base price of Michelle's cell phone plan is <math>20</math> dollars.  
If she sent 100 text messages and it costs 5 cents per text, then she must have spent 500 cents for texting, or <dollar/>5. She talked for 30.5 hours, but 30.5-30 will give us the amount of time that she has to pay an additional amount for.  
+
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.
30.5-30=.5 hours=30 minutes.
+
<math>30.5-30=.5</math> hours <math>=30</math> 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 <dollar/>3.
+
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 <dollar/>20+<dollar/>5+<dollar/>3=<dollar/>28=<math>\boxed{\textbf{D}}</math>.
+
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