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Finding the Fourth Proportional to 76.76, 105.90 and 65.80

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Solution

The fourth proportional to 76.76, 105.90 and 65.80 is: 90.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.76 : 105.90 = 65.80 : x
  2. Step 2: Convert to fraction form
    76.76/105.90 = 65.80/x
  3. Step 3: Cross multiply
    76.76x = 105.90 × 65.80
  4. Step 4: Simplify right side
    76.76x = 6,968.22
  5. Step 5: Solve for x
    x = 6,968.22/76.76
  6. Step 6: Final answer
    x = 90.78

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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.