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Finding the Fourth Proportional to 557, 768.40 and 391.15

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Solution

The fourth proportional to 557, 768.40 and 391.15 is: 539.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    557 : 768.40 = 391.15 : x
  2. Step 2: Convert to fraction form
    557/768.40 = 391.15/x
  3. Step 3: Cross multiply
    557x = 768.40 × 391.15
  4. Step 4: Simplify right side
    557x = 300,559.66
  5. Step 5: Solve for x
    x = 300,559.66/557
  6. Step 6: Final answer
    x = 539.60

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.