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Finding the Fourth Proportional to 85.82, 129.20 and 77

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Solution

The fourth proportional to 85.82, 129.20 and 77 is: 115.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.82 : 129.20 = 77 : x
  2. Step 2: Convert to fraction form
    85.82/129.20 = 77/x
  3. Step 3: Cross multiply
    85.82x = 129.20 × 77
  4. Step 4: Simplify right side
    85.82x = 9,948.40
  5. Step 5: Solve for x
    x = 9,948.40/85.82
  6. Step 6: Final answer
    x = 115.92

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Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.