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Finding the Fourth Proportional to 86, 128.82 and 79

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Solution

The fourth proportional to 86, 128.82 and 79 is: 118.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    86 : 128.82 = 79 : x
  2. Step 2: Convert to fraction form
    86/128.82 = 79/x
  3. Step 3: Cross multiply
    86x = 128.82 × 79
  4. Step 4: Simplify right side
    86x = 10,176.78
  5. Step 5: Solve for x
    x = 10,176.78/86
  6. Step 6: Final answer
    x = 118.33

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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.