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Finding the Fourth Proportional to 56.80, 85.15 and 20.72

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Solution

The fourth proportional to 56.80, 85.15 and 20.72 is: 31.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    56.80 : 85.15 = 20.72 : x
  2. Step 2: Convert to fraction form
    56.80/85.15 = 20.72/x
  3. Step 3: Cross multiply
    56.80x = 85.15 × 20.72
  4. Step 4: Simplify right side
    56.80x = 1,764.20
  5. Step 5: Solve for x
    x = 1,764.20/56.80
  6. Step 6: Final answer
    x = 31.06

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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.