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Finding the Fourth Proportional to 87.77, 121.13 and 65.90

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Solution

The fourth proportional to 87.77, 121.13 and 65.90 is: 90.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.77 : 121.13 = 65.90 : x
  2. Step 2: Convert to fraction form
    87.77/121.13 = 65.90/x
  3. Step 3: Cross multiply
    87.77x = 121.13 × 65.90
  4. Step 4: Simplify right side
    87.77x = 7,982.47
  5. Step 5: Solve for x
    x = 7,982.47/87.77
  6. Step 6: Final answer
    x = 90.95

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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.