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Finding the Fourth Proportional to 21.88, 32.78 and 12.87

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Solution

The fourth proportional to 21.88, 32.78 and 12.87 is: 19.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.88 : 32.78 = 12.87 : x
  2. Step 2: Convert to fraction form
    21.88/32.78 = 12.87/x
  3. Step 3: Cross multiply
    21.88x = 32.78 × 12.87
  4. Step 4: Simplify right side
    21.88x = 421.88
  5. Step 5: Solve for x
    x = 421.88/21.88
  6. Step 6: Final answer
    x = 19.28

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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.