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Finding the Fourth Proportional to 47.31, 70.91 and 19.88

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Solution

The fourth proportional to 47.31, 70.91 and 19.88 is: 29.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    47.31 : 70.91 = 19.88 : x
  2. Step 2: Convert to fraction form
    47.31/70.91 = 19.88/x
  3. Step 3: Cross multiply
    47.31x = 70.91 × 19.88
  4. Step 4: Simplify right side
    47.31x = 1,409.56
  5. Step 5: Solve for x
    x = 1,409.56/47.31
  6. Step 6: Final answer
    x = 29.80

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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.