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Finding the Fourth Proportional to 420.40, 629.70 and 420.40

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Solution

The fourth proportional to 420.40, 629.70 and 420.40 is: 629.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.40 : 629.70 = 420.40 : x
  2. Step 2: Convert to fraction form
    420.40/629.70 = 420.40/x
  3. Step 3: Cross multiply
    420.40x = 629.70 × 420.40
  4. Step 4: Simplify right side
    420.40x = 264,725.88
  5. Step 5: Solve for x
    x = 264,725.88/420.40
  6. Step 6: Final answer
    x = 629.70

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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.