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Finding the Fourth Proportional to 76.85, 106.31 and 65.91

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Solution

The fourth proportional to 76.85, 106.31 and 65.91 is: 91.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.85 : 106.31 = 65.91 : x
  2. Step 2: Convert to fraction form
    76.85/106.31 = 65.91/x
  3. Step 3: Cross multiply
    76.85x = 106.31 × 65.91
  4. Step 4: Simplify right side
    76.85x = 7,007.46
  5. Step 5: Solve for x
    x = 7,007.46/76.85
  6. Step 6: Final answer
    x = 91.19

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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.