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Finding the Fourth Proportional to 211.71, 292.21 and 128.85

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Solution

The fourth proportional to 211.71, 292.21 and 128.85 is: 177.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.71 : 292.21 = 128.85 : x
  2. Step 2: Convert to fraction form
    211.71/292.21 = 128.85/x
  3. Step 3: Cross multiply
    211.71x = 292.21 × 128.85
  4. Step 4: Simplify right side
    211.71x = 37,650.08
  5. Step 5: Solve for x
    x = 37,650.08/211.71
  6. Step 6: Final answer
    x = 177.84

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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.