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Finding the Fourth Proportional to 86.90, 130.64 and 76.91

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Solution

The fourth proportional to 86.90, 130.64 and 76.91 is: 115.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.90 : 130.64 = 76.91 : x
  2. Step 2: Convert to fraction form
    86.90/130.64 = 76.91/x
  3. Step 3: Cross multiply
    86.90x = 130.64 × 76.91
  4. Step 4: Simplify right side
    86.90x = 10,046.48
  5. Step 5: Solve for x
    x = 10,046.48/86.90
  6. Step 6: Final answer
    x = 115.62

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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.