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Finding the Fourth Proportional to 79.50, 109.40 and 76.86

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Solution

The fourth proportional to 79.50, 109.40 and 76.86 is: 105.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.50 : 109.40 = 76.86 : x
  2. Step 2: Convert to fraction form
    79.50/109.40 = 76.86/x
  3. Step 3: Cross multiply
    79.50x = 109.40 × 76.86
  4. Step 4: Simplify right side
    79.50x = 8,408.48
  5. Step 5: Solve for x
    x = 8,408.48/79.50
  6. Step 6: Final answer
    x = 105.77

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.