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Finding the Fourth Proportional to 87.78, 121.25 and 65.91

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Solution

The fourth proportional to 87.78, 121.25 and 65.91 is: 91.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.78 : 121.25 = 65.91 : x
  2. Step 2: Convert to fraction form
    87.78/121.25 = 65.91/x
  3. Step 3: Cross multiply
    87.78x = 121.25 × 65.91
  4. Step 4: Simplify right side
    87.78x = 7,991.59
  5. Step 5: Solve for x
    x = 7,991.59/87.78
  6. Step 6: Final answer
    x = 91.04

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.