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Finding the Fourth Proportional to 128.16, 176.76 and 86.76

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Solution

The fourth proportional to 128.16, 176.76 and 86.76 is: 119.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    128.16 : 176.76 = 86.76 : x
  2. Step 2: Convert to fraction form
    128.16/176.76 = 86.76/x
  3. Step 3: Cross multiply
    128.16x = 176.76 × 86.76
  4. Step 4: Simplify right side
    128.16x = 15,335.70
  5. Step 5: Solve for x
    x = 15,335.70/128.16
  6. Step 6: Final answer
    x = 119.66

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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.