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Finding the Fourth Proportional to 128.08, 176.68 and 86.65

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Solution

The fourth proportional to 128.08, 176.68 and 86.65 is: 119.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.08 : 176.68 = 86.65 : x
  2. Step 2: Convert to fraction form
    128.08/176.68 = 86.65/x
  3. Step 3: Cross multiply
    128.08x = 176.68 × 86.65
  4. Step 4: Simplify right side
    128.08x = 15,309.10
  5. Step 5: Solve for x
    x = 15,309.10/128.08
  6. Step 6: Final answer
    x = 119.53

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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.