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Finding the Fourth Proportional to 128.87, 177.85 and 84.64

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Solution

The fourth proportional to 128.87, 177.85 and 84.64 is: 116.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.87 : 177.85 = 84.64 : x
  2. Step 2: Convert to fraction form
    128.87/177.85 = 84.64/x
  3. Step 3: Cross multiply
    128.87x = 177.85 × 84.64
  4. Step 4: Simplify right side
    128.87x = 15,053.22
  5. Step 5: Solve for x
    x = 15,053.22/128.87
  6. Step 6: Final answer
    x = 116.81

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.