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Finding the Fourth Proportional to 128.71, 176.60 and 117.91

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Solution

The fourth proportional to 128.71, 176.60 and 117.91 is: 161.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.71 : 176.60 = 117.91 : x
  2. Step 2: Convert to fraction form
    128.71/176.60 = 117.91/x
  3. Step 3: Cross multiply
    128.71x = 176.60 × 117.91
  4. Step 4: Simplify right side
    128.71x = 20,822.91
  5. Step 5: Solve for x
    x = 20,822.91/128.71
  6. Step 6: Final answer
    x = 161.78

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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.