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Finding the Fourth Proportional to 86.51, 129.17 and 77.87

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Solution

The fourth proportional to 86.51, 129.17 and 77.87 is: 116.27

Step by Step Solution

  1. Step 1: Write the proportion equation
    86.51 : 129.17 = 77.87 : x
  2. Step 2: Convert to fraction form
    86.51/129.17 = 77.87/x
  3. Step 3: Cross multiply
    86.51x = 129.17 × 77.87
  4. Step 4: Simplify right side
    86.51x = 10,058.55
  5. Step 5: Solve for x
    x = 10,058.55/86.51
  6. Step 6: Final answer
    x = 116.27

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.