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Finding the Fourth Proportional to 21.90, 32.69 and 18.90

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Solution

The fourth proportional to 21.90, 32.69 and 18.90 is: 28.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.90 : 32.69 = 18.90 : x
  2. Step 2: Convert to fraction form
    21.90/32.69 = 18.90/x
  3. Step 3: Cross multiply
    21.90x = 32.69 × 18.90
  4. Step 4: Simplify right side
    21.90x = 617.75
  5. Step 5: Solve for x
    x = 617.75/21.90
  6. Step 6: Final answer
    x = 28.21

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.