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Finding the Fourth Proportional to 981.21, 1,469.43 and 688.98

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Solution

The fourth proportional to 981.21, 1,469.43 and 688.98 is: 1,031.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.21 : 1,469.43 = 688.98 : x
  2. Step 2: Convert to fraction form
    981.21/1,469.43 = 688.98/x
  3. Step 3: Cross multiply
    981.21x = 1,469.43 × 688.98
  4. Step 4: Simplify right side
    981.21x = 1,012,407.88
  5. Step 5: Solve for x
    x = 1,012,407.88/981.21
  6. Step 6: Final answer
    x = 1,031.80

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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.