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Finding the Fourth Proportional to 97.20, 145.80 and 86.47

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Solution

The fourth proportional to 97.20, 145.80 and 86.47 is: 129.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    97.20 : 145.80 = 86.47 : x
  2. Step 2: Convert to fraction form
    97.20/145.80 = 86.47/x
  3. Step 3: Cross multiply
    97.20x = 145.80 × 86.47
  4. Step 4: Simplify right side
    97.20x = 12,606.96
  5. Step 5: Solve for x
    x = 12,606.96/97.20
  6. Step 6: Final answer
    x = 129.70

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.