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Finding the Fourth Proportional to 84.87, 128.05 and 84.65

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Solution

The fourth proportional to 84.87, 128.05 and 84.65 is: 127.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.87 : 128.05 = 84.65 : x
  2. Step 2: Convert to fraction form
    84.87/128.05 = 84.65/x
  3. Step 3: Cross multiply
    84.87x = 128.05 × 84.65
  4. Step 4: Simplify right side
    84.87x = 10,838.58
  5. Step 5: Solve for x
    x = 10,838.58/84.87
  6. Step 6: Final answer
    x = 127.71

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.