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Finding the Fourth Proportional to 402.18, 553.42 and 391.44

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Solution

The fourth proportional to 402.18, 553.42 and 391.44 is: 538.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    402.18 : 553.42 = 391.44 : x
  2. Step 2: Convert to fraction form
    402.18/553.42 = 391.44/x
  3. Step 3: Cross multiply
    402.18x = 553.42 × 391.44
  4. Step 4: Simplify right side
    402.18x = 216,630.72
  5. Step 5: Solve for x
    x = 216,630.72/402.18
  6. Step 6: Final answer
    x = 538.64

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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.