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Finding the Fourth Proportional to 86.58, 129.70 and 69.42

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Solution

The fourth proportional to 86.58, 129.70 and 69.42 is: 103.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.58 : 129.70 = 69.42 : x
  2. Step 2: Convert to fraction form
    86.58/129.70 = 69.42/x
  3. Step 3: Cross multiply
    86.58x = 129.70 × 69.42
  4. Step 4: Simplify right side
    86.58x = 9,003.77
  5. Step 5: Solve for x
    x = 9,003.77/86.58
  6. Step 6: Final answer
    x = 103.99

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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.