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Finding the Fourth Proportional to 83.12, 124.70 and 31.78

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Solution

The fourth proportional to 83.12, 124.70 and 31.78 is: 47.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    83.12 : 124.70 = 31.78 : x
  2. Step 2: Convert to fraction form
    83.12/124.70 = 31.78/x
  3. Step 3: Cross multiply
    83.12x = 124.70 × 31.78
  4. Step 4: Simplify right side
    83.12x = 3,962.97
  5. Step 5: Solve for x
    x = 3,962.97/83.12
  6. Step 6: Final answer
    x = 47.68

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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.