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Finding the Fourth Proportional to 824.78, 1,235.70 and 688.70

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Solution

The fourth proportional to 824.78, 1,235.70 and 688.70 is: 1,031.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    824.78 : 1,235.70 = 688.70 : x
  2. Step 2: Convert to fraction form
    824.78/1,235.70 = 688.70/x
  3. Step 3: Cross multiply
    824.78x = 1,235.70 × 688.70
  4. Step 4: Simplify right side
    824.78x = 851,026.59
  5. Step 5: Solve for x
    x = 851,026.59/824.78
  6. Step 6: Final answer
    x = 1,031.82

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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.