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Finding the Fourth Proportional to 14, 21 and 13.80

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Solution

The fourth proportional to 14, 21 and 13.80 is: 20.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    14 : 21 = 13.80 : x
  2. Step 2: Convert to fraction form
    14/21 = 13.80/x
  3. Step 3: Cross multiply
    14x = 21 × 13.80
  4. Step 4: Simplify right side
    14x = 289.80
  5. Step 5: Solve for x
    x = 289.80/14
  6. Step 6: Final answer
    x = 20.70

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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.