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Finding the Fourth Proportional to 155.72, 215.17 and 128.07

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Solution

The fourth proportional to 155.72, 215.17 and 128.07 is: 176.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    155.72 : 215.17 = 128.07 : x
  2. Step 2: Convert to fraction form
    155.72/215.17 = 128.07/x
  3. Step 3: Cross multiply
    155.72x = 215.17 × 128.07
  4. Step 4: Simplify right side
    155.72x = 27,556.50
  5. Step 5: Solve for x
    x = 27,556.50/155.72
  6. Step 6: Final answer
    x = 176.96

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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.