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Finding the Fourth Proportional to 19.89, 29.79 and 13.11

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Solution

The fourth proportional to 19.89, 29.79 and 13.11 is: 19.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    19.89 : 29.79 = 13.11 : x
  2. Step 2: Convert to fraction form
    19.89/29.79 = 13.11/x
  3. Step 3: Cross multiply
    19.89x = 29.79 × 13.11
  4. Step 4: Simplify right side
    19.89x = 390.55
  5. Step 5: Solve for x
    x = 390.55/19.89
  6. Step 6: Final answer
    x = 19.64

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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.