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Finding the Fourth Proportional to 390.72, 539.92 and 320.75

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Solution

The fourth proportional to 390.72, 539.92 and 320.75 is: 443.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.72 : 539.92 = 320.75 : x
  2. Step 2: Convert to fraction form
    390.72/539.92 = 320.75/x
  3. Step 3: Cross multiply
    390.72x = 539.92 × 320.75
  4. Step 4: Simplify right side
    390.72x = 173,179.34
  5. Step 5: Solve for x
    x = 173,179.34/390.72
  6. Step 6: Final answer
    x = 443.23

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.