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Finding the Fourth Proportional to 520.28, 780.12 and 391.76

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Solution

The fourth proportional to 520.28, 780.12 and 391.76 is: 587.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    520.28 : 780.12 = 391.76 : x
  2. Step 2: Convert to fraction form
    520.28/780.12 = 391.76/x
  3. Step 3: Cross multiply
    520.28x = 780.12 × 391.76
  4. Step 4: Simplify right side
    520.28x = 305,619.81
  5. Step 5: Solve for x
    x = 305,619.81/520.28
  6. Step 6: Final answer
    x = 587.41

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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.