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Finding the Fourth Proportional to 21.90, 32.87 and 12.89

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Solution

The fourth proportional to 21.90, 32.87 and 12.89 is: 19.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.90 : 32.87 = 12.89 : x
  2. Step 2: Convert to fraction form
    21.90/32.87 = 12.89/x
  3. Step 3: Cross multiply
    21.90x = 32.87 × 12.89
  4. Step 4: Simplify right side
    21.90x = 423.81
  5. Step 5: Solve for x
    x = 423.81/21.90
  6. Step 6: Final answer
    x = 19.35

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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.