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Finding the Fourth Proportional to 420.12, 627.12 and 389.28

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Solution

The fourth proportional to 420.12, 627.12 and 389.28 is: 581.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.12 : 627.12 = 389.28 : x
  2. Step 2: Convert to fraction form
    420.12/627.12 = 389.28/x
  3. Step 3: Cross multiply
    420.12x = 627.12 × 389.28
  4. Step 4: Simplify right side
    420.12x = 244,125.27
  5. Step 5: Solve for x
    x = 244,125.27/420.12
  6. Step 6: Final answer
    x = 581.08

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.