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Finding the Fourth Proportional to 19.85, 29.70 and 15.31

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Solution

The fourth proportional to 19.85, 29.70 and 15.31 is: 22.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.85 : 29.70 = 15.31 : x
  2. Step 2: Convert to fraction form
    19.85/29.70 = 15.31/x
  3. Step 3: Cross multiply
    19.85x = 29.70 × 15.31
  4. Step 4: Simplify right side
    19.85x = 454.71
  5. Step 5: Solve for x
    x = 454.71/19.85
  6. Step 6: Final answer
    x = 22.91

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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.