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Finding the Fourth Proportional to 21.09, 31.50 and 19.92

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Solution

The fourth proportional to 21.09, 31.50 and 19.92 is: 29.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    21.09 : 31.50 = 19.92 : x
  2. Step 2: Convert to fraction form
    21.09/31.50 = 19.92/x
  3. Step 3: Cross multiply
    21.09x = 31.50 × 19.92
  4. Step 4: Simplify right side
    21.09x = 627.44
  5. Step 5: Solve for x
    x = 627.44/21.09
  6. Step 6: Final answer
    x = 29.75

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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.