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Finding the Fourth Proportional to 85.95, 128.89 and 40.31

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Solution

The fourth proportional to 85.95, 128.89 and 40.31 is: 60.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.95 : 128.89 = 40.31 : x
  2. Step 2: Convert to fraction form
    85.95/128.89 = 40.31/x
  3. Step 3: Cross multiply
    85.95x = 128.89 × 40.31
  4. Step 4: Simplify right side
    85.95x = 5,195.78
  5. Step 5: Solve for x
    x = 5,195.78/85.95
  6. Step 6: Final answer
    x = 60.45

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.