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Finding the Fourth Proportional to 981.72, 1,472.66 and 639

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Solution

The fourth proportional to 981.72, 1,472.66 and 639 is: 958.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.72 : 1,472.66 = 639 : x
  2. Step 2: Convert to fraction form
    981.72/1,472.66 = 639/x
  3. Step 3: Cross multiply
    981.72x = 1,472.66 × 639
  4. Step 4: Simplify right side
    981.72x = 941,029.74
  5. Step 5: Solve for x
    x = 941,029.74/981.72
  6. Step 6: Final answer
    x = 958.55

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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.