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Finding the Fourth Proportional to 51.15, 76.77 and 20.72

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Solution

The fourth proportional to 51.15, 76.77 and 20.72 is: 31.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    51.15 : 76.77 = 20.72 : x
  2. Step 2: Convert to fraction form
    51.15/76.77 = 20.72/x
  3. Step 3: Cross multiply
    51.15x = 76.77 × 20.72
  4. Step 4: Simplify right side
    51.15x = 1,590.29
  5. Step 5: Solve for x
    x = 1,590.29/51.15
  6. Step 6: Final answer
    x = 31.09

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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.