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Finding the Fourth Proportional to 128.78, 176.49 and 124.86

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Solution

The fourth proportional to 128.78, 176.49 and 124.86 is: 171.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.78 : 176.49 = 124.86 : x
  2. Step 2: Convert to fraction form
    128.78/176.49 = 124.86/x
  3. Step 3: Cross multiply
    128.78x = 176.49 × 124.86
  4. Step 4: Simplify right side
    128.78x = 22,037.20
  5. Step 5: Solve for x
    x = 22,037.20/128.78
  6. Step 6: Final answer
    x = 171.12

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.