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Finding the Fourth Proportional to 211.61, 291.89 and 128.63

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Solution

The fourth proportional to 211.61, 291.89 and 128.63 is: 177.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.61 : 291.89 = 128.63 : x
  2. Step 2: Convert to fraction form
    211.61/291.89 = 128.63/x
  3. Step 3: Cross multiply
    211.61x = 291.89 × 128.63
  4. Step 4: Simplify right side
    211.61x = 37,545.17
  5. Step 5: Solve for x
    x = 37,545.17/211.61
  6. Step 6: Final answer
    x = 177.43

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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.