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Finding the Fourth Proportional to 90.85, 136.42 and 56.81

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Solution

The fourth proportional to 90.85, 136.42 and 56.81 is: 85.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    90.85 : 136.42 = 56.81 : x
  2. Step 2: Convert to fraction form
    90.85/136.42 = 56.81/x
  3. Step 3: Cross multiply
    90.85x = 136.42 × 56.81
  4. Step 4: Simplify right side
    90.85x = 7,750.02
  5. Step 5: Solve for x
    x = 7,750.02/90.85
  6. Step 6: Final answer
    x = 85.31

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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.