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Finding the Fourth Proportional to 817.20, 1,225.80 and 385.20

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Solution

The fourth proportional to 817.20, 1,225.80 and 385.20 is: 577.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    817.20 : 1,225.80 = 385.20 : x
  2. Step 2: Convert to fraction form
    817.20/1,225.80 = 385.20/x
  3. Step 3: Cross multiply
    817.20x = 1,225.80 × 385.20
  4. Step 4: Simplify right side
    817.20x = 472,178.16
  5. Step 5: Solve for x
    x = 472,178.16/817.20
  6. Step 6: Final answer
    x = 577.80

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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.