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Finding the Fourth Proportional to 86.45, 129.67 and 72.88

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Solution

The fourth proportional to 86.45, 129.67 and 72.88 is: 109.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.45 : 129.67 = 72.88 : x
  2. Step 2: Convert to fraction form
    86.45/129.67 = 72.88/x
  3. Step 3: Cross multiply
    86.45x = 129.67 × 72.88
  4. Step 4: Simplify right side
    86.45x = 9,449.84
  5. Step 5: Solve for x
    x = 9,449.84/86.45
  6. Step 6: Final answer
    x = 109.32

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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.