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Finding the Fourth Proportional to 76.34, 105.20 and 65.91

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Solution

The fourth proportional to 76.34, 105.20 and 65.91 is: 90.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.34 : 105.20 = 65.91 : x
  2. Step 2: Convert to fraction form
    76.34/105.20 = 65.91/x
  3. Step 3: Cross multiply
    76.34x = 105.20 × 65.91
  4. Step 4: Simplify right side
    76.34x = 6,934.04
  5. Step 5: Solve for x
    x = 6,934.04/76.34
  6. Step 6: Final answer
    x = 90.83

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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.