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Finding the Fourth Proportional to 421.13, 629.41 and 388.31

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Solution

The fourth proportional to 421.13, 629.41 and 388.31 is: 580.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.13 : 629.41 = 388.31 : x
  2. Step 2: Convert to fraction form
    421.13/629.41 = 388.31/x
  3. Step 3: Cross multiply
    421.13x = 629.41 × 388.31
  4. Step 4: Simplify right side
    421.13x = 244,402.08
  5. Step 5: Solve for x
    x = 244,402.08/421.13
  6. Step 6: Final answer
    x = 580.34

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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.