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Finding the Fourth Proportional to 390.79, 585.15 and 309.79

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Solution

The fourth proportional to 390.79, 585.15 and 309.79 is: 463.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.79 : 585.15 = 309.79 : x
  2. Step 2: Convert to fraction form
    390.79/585.15 = 309.79/x
  3. Step 3: Cross multiply
    390.79x = 585.15 × 309.79
  4. Step 4: Simplify right side
    390.79x = 181,273.62
  5. Step 5: Solve for x
    x = 181,273.62/390.79
  6. Step 6: Final answer
    x = 463.86

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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.