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Finding the Fourth Proportional to 420.70, 629.70 and 328.90

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Solution

The fourth proportional to 420.70, 629.70 and 328.90 is: 492.29

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.70 : 629.70 = 328.90 : x
  2. Step 2: Convert to fraction form
    420.70/629.70 = 328.90/x
  3. Step 3: Cross multiply
    420.70x = 629.70 × 328.90
  4. Step 4: Simplify right side
    420.70x = 207,108.33
  5. Step 5: Solve for x
    x = 207,108.33/420.70
  6. Step 6: Final answer
    x = 492.29

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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.