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Finding the Fourth Proportional to 929.20, 1,392.72 and 639.76

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Solution

The fourth proportional to 929.20, 1,392.72 and 639.76 is: 958.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    929.20 : 1,392.72 = 639.76 : x
  2. Step 2: Convert to fraction form
    929.20/1,392.72 = 639.76/x
  3. Step 3: Cross multiply
    929.20x = 1,392.72 × 639.76
  4. Step 4: Simplify right side
    929.20x = 891,006.55
  5. Step 5: Solve for x
    x = 891,006.55/929.20
  6. Step 6: Final answer
    x = 958.90

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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.