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Finding the Fourth Proportional to 215.80, 297.79 and 128.47

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Solution

The fourth proportional to 215.80, 297.79 and 128.47 is: 177.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.80 : 297.79 = 128.47 : x
  2. Step 2: Convert to fraction form
    215.80/297.79 = 128.47/x
  3. Step 3: Cross multiply
    215.80x = 297.79 × 128.47
  4. Step 4: Simplify right side
    215.80x = 38,257.08
  5. Step 5: Solve for x
    x = 38,257.08/215.80
  6. Step 6: Final answer
    x = 177.28

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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.