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Finding the Fourth Proportional to 815.76, 1,220.79 and 667.80

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Solution

The fourth proportional to 815.76, 1,220.79 and 667.80 is: 999.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.76 : 1,220.79 = 667.80 : x
  2. Step 2: Convert to fraction form
    815.76/1,220.79 = 667.80/x
  3. Step 3: Cross multiply
    815.76x = 1,220.79 × 667.80
  4. Step 4: Simplify right side
    815.76x = 815,243.56
  5. Step 5: Solve for x
    x = 815,243.56/815.76
  6. Step 6: Final answer
    x = 999.37

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.