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Finding the Fourth Proportional to 91.20, 136.80 and 56.85

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Solution

The fourth proportional to 91.20, 136.80 and 56.85 is: 85.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    91.20 : 136.80 = 56.85 : x
  2. Step 2: Convert to fraction form
    91.20/136.80 = 56.85/x
  3. Step 3: Cross multiply
    91.20x = 136.80 × 56.85
  4. Step 4: Simplify right side
    91.20x = 7,777.08
  5. Step 5: Solve for x
    x = 7,777.08/91.20
  6. Step 6: Final answer
    x = 85.28

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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.