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Finding the Fourth Proportional to 87.71, 121.09 and 77.98

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Solution

The fourth proportional to 87.71, 121.09 and 77.98 is: 107.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.71 : 121.09 = 77.98 : x
  2. Step 2: Convert to fraction form
    87.71/121.09 = 77.98/x
  3. Step 3: Cross multiply
    87.71x = 121.09 × 77.98
  4. Step 4: Simplify right side
    87.71x = 9,443.18
  5. Step 5: Solve for x
    x = 9,443.18/87.71
  6. Step 6: Final answer
    x = 107.66

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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.