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Finding the Fourth Proportional to 420.36, 629.61 and 257.55

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Solution

The fourth proportional to 420.36, 629.61 and 257.55 is: 385.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.36 : 629.61 = 257.55 : x
  2. Step 2: Convert to fraction form
    420.36/629.61 = 257.55/x
  3. Step 3: Cross multiply
    420.36x = 629.61 × 257.55
  4. Step 4: Simplify right side
    420.36x = 162,156.06
  5. Step 5: Solve for x
    x = 162,156.06/420.36
  6. Step 6: Final answer
    x = 385.76

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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.