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Finding the Fourth Proportional to 31.78, 47.60 and 19.72

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Solution

The fourth proportional to 31.78, 47.60 and 19.72 is: 29.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    31.78 : 47.60 = 19.72 : x
  2. Step 2: Convert to fraction form
    31.78/47.60 = 19.72/x
  3. Step 3: Cross multiply
    31.78x = 47.60 × 19.72
  4. Step 4: Simplify right side
    31.78x = 938.67
  5. Step 5: Solve for x
    x = 938.67/31.78
  6. Step 6: Final answer
    x = 29.54

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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.