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Finding the Fourth Proportional to 639.42, 958.92 and 421.56

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Solution

The fourth proportional to 639.42, 958.92 and 421.56 is: 632.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.42 : 958.92 = 421.56 : x
  2. Step 2: Convert to fraction form
    639.42/958.92 = 421.56/x
  3. Step 3: Cross multiply
    639.42x = 958.92 × 421.56
  4. Step 4: Simplify right side
    639.42x = 404,242.32
  5. Step 5: Solve for x
    x = 404,242.32/639.42
  6. Step 6: Final answer
    x = 632.20

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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.