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Finding the Fourth Proportional to 402.87, 555.99 and 390.12

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Solution

The fourth proportional to 402.87, 555.99 and 390.12 is: 538.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    402.87 : 555.99 = 390.12 : x
  2. Step 2: Convert to fraction form
    402.87/555.99 = 390.12/x
  3. Step 3: Cross multiply
    402.87x = 555.99 × 390.12
  4. Step 4: Simplify right side
    402.87x = 216,902.82
  5. Step 5: Solve for x
    x = 216,902.82/402.87
  6. Step 6: Final answer
    x = 538.39

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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.