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Finding the Fourth Proportional to 128.42, 177.09 and 84.74

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Solution

The fourth proportional to 128.42, 177.09 and 84.74 is: 116.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.42 : 177.09 = 84.74 : x
  2. Step 2: Convert to fraction form
    128.42/177.09 = 84.74/x
  3. Step 3: Cross multiply
    128.42x = 177.09 × 84.74
  4. Step 4: Simplify right side
    128.42x = 15,006.61
  5. Step 5: Solve for x
    x = 15,006.61/128.42
  6. Step 6: Final answer
    x = 116.86

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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.