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Finding the Fourth Proportional to 109.68, 163.68 and 86.76

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Solution

The fourth proportional to 109.68, 163.68 and 86.76 is: 129.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    109.68 : 163.68 = 86.76 : x
  2. Step 2: Convert to fraction form
    109.68/163.68 = 86.76/x
  3. Step 3: Cross multiply
    109.68x = 163.68 × 86.76
  4. Step 4: Simplify right side
    109.68x = 14,200.88
  5. Step 5: Solve for x
    x = 14,200.88/109.68
  6. Step 6: Final answer
    x = 129.48

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.