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Finding the Fourth Proportional to 420, 628.32 and 257.28

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Solution

The fourth proportional to 420, 628.32 and 257.28 is: 384.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    420 : 628.32 = 257.28 : x
  2. Step 2: Convert to fraction form
    420/628.32 = 257.28/x
  3. Step 3: Cross multiply
    420x = 628.32 × 257.28
  4. Step 4: Simplify right side
    420x = 161,654.17
  5. Step 5: Solve for x
    x = 161,654.17/420
  6. Step 6: Final answer
    x = 384.89

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.