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Finding the Fourth Proportional to 815.90, 1,221.39 and 572.28

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Solution

The fourth proportional to 815.90, 1,221.39 and 572.28 is: 856.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.90 : 1,221.39 = 572.28 : x
  2. Step 2: Convert to fraction form
    815.90/1,221.39 = 572.28/x
  3. Step 3: Cross multiply
    815.90x = 1,221.39 × 572.28
  4. Step 4: Simplify right side
    815.90x = 698,977.07
  5. Step 5: Solve for x
    x = 698,977.07/815.90
  6. Step 6: Final answer
    x = 856.70

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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.