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Finding the Fourth Proportional to 815.70, 1,221.12 and 554.20

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Solution

The fourth proportional to 815.70, 1,221.12 and 554.20 is: 829.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.70 : 1,221.12 = 554.20 : x
  2. Step 2: Convert to fraction form
    815.70/1,221.12 = 554.20/x
  3. Step 3: Cross multiply
    815.70x = 1,221.12 × 554.20
  4. Step 4: Simplify right side
    815.70x = 676,744.70
  5. Step 5: Solve for x
    x = 676,744.70/815.70
  6. Step 6: Final answer
    x = 829.65

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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.