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Finding the Fourth Proportional to 83.76, 124.74 and 81.72

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Solution

The fourth proportional to 83.76, 124.74 and 81.72 is: 121.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    83.76 : 124.74 = 81.72 : x
  2. Step 2: Convert to fraction form
    83.76/124.74 = 81.72/x
  3. Step 3: Cross multiply
    83.76x = 124.74 × 81.72
  4. Step 4: Simplify right side
    83.76x = 10,193.75
  5. Step 5: Solve for x
    x = 10,193.75/83.76
  6. Step 6: Final answer
    x = 121.70

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.