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Finding the Fourth Proportional to 128.55, 177.15 and 100.92

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Solution

The fourth proportional to 128.55, 177.15 and 100.92 is: 139.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.55 : 177.15 = 100.92 : x
  2. Step 2: Convert to fraction form
    128.55/177.15 = 100.92/x
  3. Step 3: Cross multiply
    128.55x = 177.15 × 100.92
  4. Step 4: Simplify right side
    128.55x = 17,877.98
  5. Step 5: Solve for x
    x = 17,877.98/128.55
  6. Step 6: Final answer
    x = 139.07

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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.