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Finding the Fourth Proportional to 628.21, 939.88 and 421.80

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Solution

The fourth proportional to 628.21, 939.88 and 421.80 is: 631.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    628.21 : 939.88 = 421.80 : x
  2. Step 2: Convert to fraction form
    628.21/939.88 = 421.80/x
  3. Step 3: Cross multiply
    628.21x = 939.88 × 421.80
  4. Step 4: Simplify right side
    628.21x = 396,441.38
  5. Step 5: Solve for x
    x = 396,441.38/628.21
  6. Step 6: Final answer
    x = 631.07

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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.