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Finding the Fourth Proportional to 87.31, 130.71 and 78.05

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Solution

The fourth proportional to 87.31, 130.71 and 78.05 is: 116.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.31 : 130.71 = 78.05 : x
  2. Step 2: Convert to fraction form
    87.31/130.71 = 78.05/x
  3. Step 3: Cross multiply
    87.31x = 130.71 × 78.05
  4. Step 4: Simplify right side
    87.31x = 10,201.80
  5. Step 5: Solve for x
    x = 10,201.80/87.31
  6. Step 6: Final answer
    x = 116.84

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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.