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Finding the Fourth Proportional to 76.89, 115.20 and 64.78

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Solution

The fourth proportional to 76.89, 115.20 and 64.78 is: 97.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    76.89 : 115.20 = 64.78 : x
  2. Step 2: Convert to fraction form
    76.89/115.20 = 64.78/x
  3. Step 3: Cross multiply
    76.89x = 115.20 × 64.78
  4. Step 4: Simplify right side
    76.89x = 7,462.66
  5. Step 5: Solve for x
    x = 7,462.66/76.89
  6. Step 6: Final answer
    x = 97.06

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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.