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Finding the Fourth Proportional to 86.27, 129.40 and 72.90

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Solution

The fourth proportional to 86.27, 129.40 and 72.90 is: 109.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.27 : 129.40 = 72.90 : x
  2. Step 2: Convert to fraction form
    86.27/129.40 = 72.90/x
  3. Step 3: Cross multiply
    86.27x = 129.40 × 72.90
  4. Step 4: Simplify right side
    86.27x = 9,433.08
  5. Step 5: Solve for x
    x = 9,433.08/86.27
  6. Step 6: Final answer
    x = 109.35

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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.