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Finding the Fourth Proportional to 679.92, 938.40 and 385.20

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Solution

The fourth proportional to 679.92, 938.40 and 385.20 is: 531.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    679.92 : 938.40 = 385.20 : x
  2. Step 2: Convert to fraction form
    679.92/938.40 = 385.20/x
  3. Step 3: Cross multiply
    679.92x = 938.40 × 385.20
  4. Step 4: Simplify right side
    679.92x = 361,471.68
  5. Step 5: Solve for x
    x = 361,471.68/679.92
  6. Step 6: Final answer
    x = 531.64

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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.