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Finding the Fourth Proportional to 215.66, 297.66 and 128.40

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Solution

The fourth proportional to 215.66, 297.66 and 128.40 is: 177.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    215.66 : 297.66 = 128.40 : x
  2. Step 2: Convert to fraction form
    215.66/297.66 = 128.40/x
  3. Step 3: Cross multiply
    215.66x = 297.66 × 128.40
  4. Step 4: Simplify right side
    215.66x = 38,219.54
  5. Step 5: Solve for x
    x = 38,219.54/215.66
  6. Step 6: Final answer
    x = 177.22

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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.