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Finding the Fourth Proportional to 211.64, 291.91 and 128.73

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Solution

The fourth proportional to 211.64, 291.91 and 128.73 is: 177.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.64 : 291.91 = 128.73 : x
  2. Step 2: Convert to fraction form
    211.64/291.91 = 128.73/x
  3. Step 3: Cross multiply
    211.64x = 291.91 × 128.73
  4. Step 4: Simplify right side
    211.64x = 37,577.57
  5. Step 5: Solve for x
    x = 37,577.57/211.64
  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.