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Finding the Fourth Proportional to 211.38, 291.75 and 128.49

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Solution

The fourth proportional to 211.38, 291.75 and 128.49 is: 177.34

Step by Step Solution

  1. Step 1: Write the proportion equation
    211.38 : 291.75 = 128.49 : x
  2. Step 2: Convert to fraction form
    211.38/291.75 = 128.49/x
  3. Step 3: Cross multiply
    211.38x = 291.75 × 128.49
  4. Step 4: Simplify right side
    211.38x = 37,486.96
  5. Step 5: Solve for x
    x = 37,486.96/211.38
  6. Step 6: Final answer
    x = 177.34

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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.