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Finding the Fourth Proportional to 86, 128.72 and 65.52

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Solution

The fourth proportional to 86, 128.72 and 65.52 is: 98.07

Step by Step Solution

  1. Step 1: Write the proportion equation
    86 : 128.72 = 65.52 : x
  2. Step 2: Convert to fraction form
    86/128.72 = 65.52/x
  3. Step 3: Cross multiply
    86x = 128.72 × 65.52
  4. Step 4: Simplify right side
    86x = 8,433.73
  5. Step 5: Solve for x
    x = 8,433.73/86
  6. Step 6: Final answer
    x = 98.07

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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.