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Finding the Fourth Proportional to 520.38, 780.56 and 212.40

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Solution

The fourth proportional to 520.38, 780.56 and 212.40 is: 318.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    520.38 : 780.56 = 212.40 : x
  2. Step 2: Convert to fraction form
    520.38/780.56 = 212.40/x
  3. Step 3: Cross multiply
    520.38x = 780.56 × 212.40
  4. Step 4: Simplify right side
    520.38x = 165,790.94
  5. Step 5: Solve for x
    x = 165,790.94/520.38
  6. Step 6: Final answer
    x = 318.60

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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.