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Finding the Fourth Proportional to 217.39, 299.97 and 128.90

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Solution

The fourth proportional to 217.39, 299.97 and 128.90 is: 177.87

Step by Step Solution

  1. Step 1: Write the proportion equation
    217.39 : 299.97 = 128.90 : x
  2. Step 2: Convert to fraction form
    217.39/299.97 = 128.90/x
  3. Step 3: Cross multiply
    217.39x = 299.97 × 128.90
  4. Step 4: Simplify right side
    217.39x = 38,666.13
  5. Step 5: Solve for x
    x = 38,666.13/217.39
  6. Step 6: Final answer
    x = 177.87

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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.