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Finding the Fourth Proportional to 76.88, 106.09 and 47.78

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Solution

The fourth proportional to 76.88, 106.09 and 47.78 is: 65.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.88 : 106.09 = 47.78 : x
  2. Step 2: Convert to fraction form
    76.88/106.09 = 47.78/x
  3. Step 3: Cross multiply
    76.88x = 106.09 × 47.78
  4. Step 4: Simplify right side
    76.88x = 5,069.13
  5. Step 5: Solve for x
    x = 5,069.13/76.88
  6. Step 6: Final answer
    x = 65.94

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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.