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Finding the Fourth Proportional to 128.32, 177.13 and 86.86

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Solution

The fourth proportional to 128.32, 177.13 and 86.86 is: 119.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.32 : 177.13 = 86.86 : x
  2. Step 2: Convert to fraction form
    128.32/177.13 = 86.86/x
  3. Step 3: Cross multiply
    128.32x = 177.13 × 86.86
  4. Step 4: Simplify right side
    128.32x = 15,385.51
  5. Step 5: Solve for x
    x = 15,385.51/128.32
  6. Step 6: Final answer
    x = 119.90

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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.