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Finding the Fourth Proportional to 18.70, 28.00 and 13.89

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Solution

The fourth proportional to 18.70, 28.00 and 13.89 is: 20.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.70 : 28.00 = 13.89 : x
  2. Step 2: Convert to fraction form
    18.70/28.00 = 13.89/x
  3. Step 3: Cross multiply
    18.70x = 28.00 × 13.89
  4. Step 4: Simplify right side
    18.70x = 388.89
  5. Step 5: Solve for x
    x = 388.89/18.70
  6. Step 6: Final answer
    x = 20.80

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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.