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Finding the Fourth Proportional to 85.86, 129.06 and 72.36

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Solution

The fourth proportional to 85.86, 129.06 and 72.36 is: 108.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.86 : 129.06 = 72.36 : x
  2. Step 2: Convert to fraction form
    85.86/129.06 = 72.36/x
  3. Step 3: Cross multiply
    85.86x = 129.06 × 72.36
  4. Step 4: Simplify right side
    85.86x = 9,338.78
  5. Step 5: Solve for x
    x = 9,338.78/85.86
  6. Step 6: Final answer
    x = 108.77

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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.