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Finding the Fourth Proportional to 639.45, 961.20 and 458.10

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Solution

The fourth proportional to 639.45, 961.20 and 458.10 is: 688.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.45 : 961.20 = 458.10 : x
  2. Step 2: Convert to fraction form
    639.45/961.20 = 458.10/x
  3. Step 3: Cross multiply
    639.45x = 961.20 × 458.10
  4. Step 4: Simplify right side
    639.45x = 440,325.72
  5. Step 5: Solve for x
    x = 440,325.72/639.45
  6. Step 6: Final answer
    x = 688.60

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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.