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Finding the Fourth Proportional to 87.90, 120.48 and 86.64

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Solution

The fourth proportional to 87.90, 120.48 and 86.64 is: 118.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.90 : 120.48 = 86.64 : x
  2. Step 2: Convert to fraction form
    87.90/120.48 = 86.64/x
  3. Step 3: Cross multiply
    87.90x = 120.48 × 86.64
  4. Step 4: Simplify right side
    87.90x = 10,438.39
  5. Step 5: Solve for x
    x = 10,438.39/87.90
  6. Step 6: Final answer
    x = 118.75

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.