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Finding the Fourth Proportional to 86.00, 128.79 and 51.30

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Solution

The fourth proportional to 86.00, 128.79 and 51.30 is: 76.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.00 : 128.79 = 51.30 : x
  2. Step 2: Convert to fraction form
    86.00/128.79 = 51.30/x
  3. Step 3: Cross multiply
    86.00x = 128.79 × 51.30
  4. Step 4: Simplify right side
    86.00x = 6,606.93
  5. Step 5: Solve for x
    x = 6,606.93/86.00
  6. Step 6: Final answer
    x = 76.83

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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.