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Finding the Fourth Proportional to 21.05, 29.05 and 12.87

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Solution

The fourth proportional to 21.05, 29.05 and 12.87 is: 17.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.05 : 29.05 = 12.87 : x
  2. Step 2: Convert to fraction form
    21.05/29.05 = 12.87/x
  3. Step 3: Cross multiply
    21.05x = 29.05 × 12.87
  4. Step 4: Simplify right side
    21.05x = 373.87
  5. Step 5: Solve for x
    x = 373.87/21.05
  6. Step 6: Final answer
    x = 17.76

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.