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Finding the Fourth Proportional to 217.21, 299.71 and 128.68

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Solution

The fourth proportional to 217.21, 299.71 and 128.68 is: 177.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    217.21 : 299.71 = 128.68 : x
  2. Step 2: Convert to fraction form
    217.21/299.71 = 128.68/x
  3. Step 3: Cross multiply
    217.21x = 299.71 × 128.68
  4. Step 4: Simplify right side
    217.21x = 38,565.61
  5. Step 5: Solve for x
    x = 38,565.61/217.21
  6. Step 6: Final answer
    x = 177.55

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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.