Florida B.E.S.T. MA.912.FL.1.3
The Standard
Solve real-world problems involving weighted averages using spreadsheets and other technology.
Florida B.E.S.T. Standards for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students calculate an overall value when financial amounts contribute unequally, such as investments with different balances. They enter data and formulas in a spreadsheet, then interpret the result in context.
What Mastery Looks Like
- Students organize values and weights in labeled spreadsheet columns and use a correct formula, such as SUMPRODUCT divided by total weight. They check units and explain what the result means financially.
Common Misconceptions
- Students may use a simple mean even when the dollar amounts differ. They may confuse values with weights, enter 8% as 8, or omit division by the total weight.
How to Assess It
- Give students investments of $2,000 at 4%, $3,000 at 6%, and $5,000 at 9%. Ask for a spreadsheet formula, the weighted return, and one sentence interpreting the result.
Lesson moves
Ways to Teach It
Give pairs investment cards with different balances and returns, then have them arrange the data and calculate the portfolio return in a spreadsheet.
Ask students to explain why averaging 3% and 9% can give a misleading result when the invested amounts are different.
Run a spreadsheet error hunt where teams correct formulas containing swapped cells, missing totals, and percentages entered as whole numbers.
Compare weighted interest rates for three loan offers with different borrowed amounts, then identify which combined borrowing plan costs less.
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Related Standards
- MA.912.FL.2.2
Solve real-world problems involving profits, costs and revenues using spreadsheets and other technology.
- MA.912.FL.2.1
Given assets and liabilities, calculate net worth using spreadsheets and other technology.
- MA.4.DP.1.3
Solve real-world problems involving numerical data.
- MA.912.FL.2.6
Given a real-world scenario, complete and calculate federal income tax using spreadsheets and other technology.
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