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Finding the Fourth Proportional to 520.79, 780.15 and 390.93

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Solution

The fourth proportional to 520.79, 780.15 and 390.93 is: 585.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    520.79 : 780.15 = 390.93 : x
  2. Step 2: Convert to fraction form
    520.79/780.15 = 390.93/x
  3. Step 3: Cross multiply
    520.79x = 780.15 × 390.93
  4. Step 4: Simplify right side
    520.79x = 304,984.04
  5. Step 5: Solve for x
    x = 304,984.04/520.79
  6. Step 6: Final answer
    x = 585.62

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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.