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Finding the Fourth Proportional to 76.80, 115.29 and 71.13

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Solution

The fourth proportional to 76.80, 115.29 and 71.13 is: 106.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.80 : 115.29 = 71.13 : x
  2. Step 2: Convert to fraction form
    76.80/115.29 = 71.13/x
  3. Step 3: Cross multiply
    76.80x = 115.29 × 71.13
  4. Step 4: Simplify right side
    76.80x = 8,200.58
  5. Step 5: Solve for x
    x = 8,200.58/76.80
  6. Step 6: Final answer
    x = 106.78

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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.