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Finding the Fourth Proportional to 215.78, 297.65 and 128.43

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Solution

The fourth proportional to 215.78, 297.65 and 128.43 is: 177.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.78 : 297.65 = 128.43 : x
  2. Step 2: Convert to fraction form
    215.78/297.65 = 128.43/x
  3. Step 3: Cross multiply
    215.78x = 297.65 × 128.43
  4. Step 4: Simplify right side
    215.78x = 38,226.55
  5. Step 5: Solve for x
    x = 38,226.55/215.78
  6. Step 6: Final answer
    x = 177.16

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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.