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Finding the Fourth Proportional to 47.78, 71.66 and 20.72

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Solution

The fourth proportional to 47.78, 71.66 and 20.72 is: 31.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.78 : 71.66 = 20.72 : x
  2. Step 2: Convert to fraction form
    47.78/71.66 = 20.72/x
  3. Step 3: Cross multiply
    47.78x = 71.66 × 20.72
  4. Step 4: Simplify right side
    47.78x = 1,484.80
  5. Step 5: Solve for x
    x = 1,484.80/47.78
  6. Step 6: Final answer
    x = 31.08

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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.