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Finding the Fourth Proportional to 390.26, 585.12 and 280.64

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Solution

The fourth proportional to 390.26, 585.12 and 280.64 is: 420.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.26 : 585.12 = 280.64 : x
  2. Step 2: Convert to fraction form
    390.26/585.12 = 280.64/x
  3. Step 3: Cross multiply
    390.26x = 585.12 × 280.64
  4. Step 4: Simplify right side
    390.26x = 164,208.08
  5. Step 5: Solve for x
    x = 164,208.08/390.26
  6. Step 6: Final answer
    x = 420.77

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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.