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Finding the Fourth Proportional to 87.21, 130.09 and 78.09

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Solution

The fourth proportional to 87.21, 130.09 and 78.09 is: 116.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.21 : 130.09 = 78.09 : x
  2. Step 2: Convert to fraction form
    87.21/130.09 = 78.09/x
  3. Step 3: Cross multiply
    87.21x = 130.09 × 78.09
  4. Step 4: Simplify right side
    87.21x = 10,158.73
  5. Step 5: Solve for x
    x = 10,158.73/87.21
  6. Step 6: Final answer
    x = 116.49

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.