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Finding the Fourth Proportional to 85.95, 128.33 and 77.31

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Solution

The fourth proportional to 85.95, 128.33 and 77.31 is: 115.43

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.95 : 128.33 = 77.31 : x
  2. Step 2: Convert to fraction form
    85.95/128.33 = 77.31/x
  3. Step 3: Cross multiply
    85.95x = 128.33 × 77.31
  4. Step 4: Simplify right side
    85.95x = 9,921.13
  5. Step 5: Solve for x
    x = 9,921.13/85.95
  6. Step 6: Final answer
    x = 115.43

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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.