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Finding the Fourth Proportional to 83.15, 124.72 and 31.80

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Solution

The fourth proportional to 83.15, 124.72 and 31.80 is: 47.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    83.15 : 124.72 = 31.80 : x
  2. Step 2: Convert to fraction form
    83.15/124.72 = 31.80/x
  3. Step 3: Cross multiply
    83.15x = 124.72 × 31.80
  4. Step 4: Simplify right side
    83.15x = 3,966.10
  5. Step 5: Solve for x
    x = 3,966.10/83.15
  6. Step 6: Final answer
    x = 47.70

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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.