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Finding the Fourth Proportional to 85.85, 128.73 and 51.60

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Solution

The fourth proportional to 85.85, 128.73 and 51.60 is: 77.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    85.85 : 128.73 = 51.60 : x
  2. Step 2: Convert to fraction form
    85.85/128.73 = 51.60/x
  3. Step 3: Cross multiply
    85.85x = 128.73 × 51.60
  4. Step 4: Simplify right side
    85.85x = 6,642.47
  5. Step 5: Solve for x
    x = 6,642.47/85.85
  6. Step 6: Final answer
    x = 77.37

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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.