standard_description: Know the formulas for the area and circumference of a circle and use them to solve problems; give an informal derivation of the relationship between the circumference and area of a circle.
problem_activity: Problem 1
In a 30-minute television show, 12 minutes of the airtime are spent on commercials.
a.   Draw a visual representation of the problem.
b.   Determine what percent of the television show’s airtime is spent on commercials. Choose any strategy.
c.   Find a peer who used a different strategy to solve than you did. Compare and discuss your strategies and solutions.
Problem 2
Cole and Jamie are raising money for the annual Walk for Hunger in their city. They each have a goal to raise $250. So far, Cole has raised $150 and Jamie has raised $180.
a.   What percent of their goal did each boy raise so far?
b.   What is the amount that Cole raised as a percent of the amount Jamie raised?
c.   What is the amount Jamie raised as a percent of the amount Cole raised?
Problem 3
At a middle school, 480 students in sixth through eighth grade responded to a survey that asked them what their favorite season was. The circle graph below shows some of the data from the survey.
Student Survey “Favorite Season”
[IMG]
a.   How many students chose spring as their favorite season?
b.   What percent of students chose summer as their favorite season?
c.   In just the sixth-grade class, 28 students chose winter as their favorite season. This was 20% of the sixth grade. How many students are in the sixth grade at this school?


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